You're an idiot. And I'm not just saying that to be nice.
"She hasn't even read the books" - Elliot_Alderson

Isn't this question brought up about once a month?
Lolz, just saying.

Last scene in Psycho.. Norman Bates thinking aloud as his mother : "They;ll see, and they'll know. Why she wouldn't even harm a fly". lol
I guess flys will now be symbolic to Walt.. the fly(s) in the ointment. He would have been ok if everyone had just left him alone instead of all getting in his way etc. etc. Walt's truth: He didn't mean to harm a fly or anyone at all. It was all forced on him. This is common of criminals, as in the story of 'Two gun Crowly':
Dale Carnegie published his book How to Win Friends and Influence People. It has remained a classic on human nature and is still popular today. One of his chapters dealt with the fact that people never blame themselves even when they are clearly wrong. One of his examples involved "Two Gun Crowley" a killer who was finally trapped by the police in his girl friends apartment in 1931. Surrounded by police Crowley carried on a gun battle with police until captured. New Yorks police commissioner said he was one of the most dangerous criminals in the history of New York who would kill "at the drop of a feather."
Carnegie points out, however, that while Crowley was trapped in the apartment he wrote a "to whom it may concern" letter which said in part: "Under my coat is a weary heart, but a kind one one that would do nobody any harm." A short time before this, Crowley had shot a policeman to death when he asked him for his drivers license. When Crowley was sent to Sing Sing to be executed, he said "This is what I get for defending myself." The point of the story is that "Two Gun Crowley" didnt blame himself for anything.
Matrix
flo
wer

What do you think about the final scene, with Walt waking up to see the fly on the flashing red lighthad a bit of a Hitchcock feel to it, IMO.

Filth, contamination, corruption, everything has gone to hell -the only thing Walt can control now is his immediate environment, namely his cook.
In his state of exhaustion he is starting to flip out as a result of all that has happened to him and all the foul things he has done - having lost sight of his initial intent, his goal. he has been swept along by illegal and morally corupt events affecting all areas of his once safe (relatively speaking) existence. In his state of tiredness the fly is interfering in his control of his only manageable task - his cook. It is now Walt vs. The Fly . at this micromanagement level. It is all he feels he has left.. of himself. of the original real Walter White. The fly is the last straw.
Nah, most of their ingredients are filtered and cooked. What's a miniscule bit of organic waste in the size of those cooks anyway.
He is on a delusional sleep deprived spin-out where his mind mess is magnified.
Matrix
flo
wer

What does the fly symbolize? Why does Walt obsess over it so bad? Could it really ruin the batch?

Agreed! Compared to other episodes, "Fly" does indeed fall short. It's not bad in anyway, it's just not AS good as the rest of the episodes in season 4. It felt more like filler or the stuff that could've gotten edited out of a major film and put as "deleted scenes" later on.

I find the episode avarage at best: nothing happens (foreshadowing is not enough)and the tone was too comical for the series' standards (it was a fun plot though, better than most today comedies), so no wonder why people detest this.
But the second half has a nice dialogue between WW and JP, so is not to trash entirely.
"Its Not the Idea But the Execution that Matters"

Its the lowest rated episode ever so you obviously are not alone.

Good episode on first watch. Symbolic meaning/foreshadowing through it. Never understood the hate.

Late response here but just wanted to mention, Walt was a perfectionist. A grew example is the scene where he's preparing jr's lunch, how meticulously he goes about it.
He took great pride in the quality of his product. Even if it was poison for drug addicts who couldn't care less, in walts mind it had to be perfect.

Finally an honest response.
IMDb IS a good place to seek validation to the "my opinion"="right opinion". But it's pretty obnoxious.
Do you even know what honor is?

• A horse.

"Honest" just means "What I like." You insult everyone who thinks differently than you. That's dishonest.
I seriously doubt that the character would care that much about one fly in the lab given how bad the product is in and of itself for the customer, etc.
You seriously missed the nature of his character, and the context bearing on him at that point.
"You must not judge what I know by what I find words for."

• Marilynne Robinson

Finally an honest response. The acting feels affected as though the director told them to improv. The question if he tried the product is funny. And it gets a bit better at the end with Walt's apologetic dialogue. But the whole premise of the episode is off. As much as cooking meth is an art or better yet scientific project that Walt takes great pride in, I seriously doubt that the character would care that much about one fly in the lab given how bad the product is in and of itself for the customer, etc.

Well, one thing's for sure, that's a filler post.

Fly is as filler as it gets. The only good thing about it is Jesse's reaction to how incredibly autistic Walt is being about the fly. "Wait, did you try our product" or something.

Better late than never!
Every time Walt gets morose it has a huge impact on his character, and his character is obviously the driving force behind the whole story
Good point. I enjoy noting each of a protagonist's major emotional events and correleating them to major plot developments. The result is literally a map of consciousness and its external effects the psyche making the external world in its image.
I look at much drama, and life, that way. In Walt's case, the external creation was hell, arising from, and reflecting, his inner landscape.
"You must not judge what I know by what I find words for."

• Marilynne Robinson

Naturally this will have a huge impact on subsequent events, since if he's already doomed he no longer needs to hold back.
This is a really good observation. Walt says in
Fly
that his ideal life span is already over, that he should have died long ago to actually accomplish what he set out to accomplish (a certain amount of money for his family, them to remember him as he wanted to be remembered.) For those who insist Walt always did everything "for the family", it didn't take until
Felina
for him to admit that was not the case. His morose angst in Fly was enough to demonstrate he was no longer doing what he was doing for the same purpose he started with. He had already lost a certain amount of the respect he wanted his family to have, and had already made enough money, so by this episode we can safely surmise "family" isn't his driving motivation anymore (not that there isn't enough evidence for that earlier, there is since episode one of season one, but here it is outright stated.)
Every time Walt gets morose it has a huge impact on his character, and his character is obviously the driving force behind the whole story. I love all the episodes like this - 4 Days Out, Fly, Salud They give a glimpse to real Walt, behind his manipulation, behind the Heisenberg alter ego, behind his "this is how a man should be like" persona.
Oh by the way sorry for the super late reply! I re-discovered this thread due to your post in the new one.
Do you even know what honor is?

• A horse.

it doesn't really advance the plot as such
Not directly, but indirectly I think it has enormous impact.
Consider that the ep contains THE breakthrough revelation for Walt: "It's all contaminated." He now knows that corruption pursues him everywhere, that it's permanent a new fly appears in the bookended last scene.
Structurally the intersection of character and plot this ep marks the peak, terminal point of what has been Walt's long and increasingly desperate effort to deny that he is truly past the point of no return. From now on, that changes he's increasingly freed of that delusion, eventually descending to the point where Jesse watches in horror as he literally whistles while he works just after rationalizing Drew Sharp's murder.
The events in
Fly
are so intensely experienced by Walt helped by sleep-deprivation and psychotropic drugs, a mix of sleeping pills and caffeine that they are able to permanently rupture his fantasy that he's still acting righteously that he is still redeemable. He can't get relief from his conscience, he can't tell Jesse he killed Jane. "It's all contaminated" he realizes there is no escape. Except, for losing consciousness. Which literally happens in the ep. Consciousness/awareness of conscience. Thereafter, he's much better able to quarantine and pretty much eliminate from his mind this most demanding human quality.
The ep marks the point when Walt realizes he no longer has a soul to lose. Well, that's pretty much everything. Naturally this will have a huge impact on subsequent events, since if he's already doomed he no longer needs to hold back.
Fly
is about forcing a profound revelation, and that's never neutral. It always has consequences, good or bad.
"You must not judge what I know by what I find words for."

• Marilynne Robinson

I personally love the episode, although I know it is a divisive one. The Walt&Jesse interaction in it is really good, and while it doesn't really advance the plot as such, it does develop the relationship between them. Breaking Bad manages to have a rather perfect combination of being both story- and character-driven show,
Fly
definitely is pure character interaction but I love it for what it is.
Do you even know what honor is?

• A horse.

I loved the episode. Sorry, OP.

That is my favorite part of the episode. As he is falling asleep he almost says it. Only if it had spit out, can you imagine the rest of the show? Jesse loved her. Wow, love this scene

There was an especially tense moment where WW almost tells JP that he killed Jane.

I can honestly say I never got bored on any episodes