Love how the killer in this movie has this downright supernatural ability to clean up his grisly handywork in a ridiculously quick amount of time.
You've seen Guy Standeven in something because the man was in everything.

Yes, I was one of them!
(I'm not saying it's right, don't shoot the messenger!)

He says that's just what movies were like in the 90s and you either accepted it or you didn't
People also complained about it back in the 90s.

I never got the impression it was in her mind just seems typical of movies of this type in the mid 90s where these things happened and while they are unlikely, you're just supposed to go along with it.
I know it's a different genre but I read an interview with the creator of "She's All That" about the ridiculousness of casting a beautiful actress, putting glasses on her, and then expecting viewers to believe that all the other characters think she's ugly. He says that's just what movies were like in the 90s and you either accepted it or you didn't.
It's pretty lame, but hey. At least in a slasher like IKWYDLS you can suspend you disbelief a bit. So even if it's a bit unrealistic that the killer would have cleaned all that up, it's not completely outside the realms of possibility, so just go with it.

It sure seems like it, I mean how fast can you clean up a trunk with a dead body and crabs all over? Kind of like when Barry gets killed on the balcony and when they go up there is no blood or anything around? Lol

It's clear they haven't run a country mile.
Well, I didn't suggest THAT. But it could've been 10 minutes.
It just adds weight to the veracity of her claims.
But that wasn't really a problem, they seemed pretty willing to believe her.

Who knows how much time had passed.
It's clear they haven't run a country mile.
but what does that prove exactly?
It just adds weight to the veracity of her claims. Corpse and crustacean odours are both rather hard to eradicate with a wipe of a cloth.
a scene like that is very typical for a teen slasher.
Said virtually the same thing on another thread unfortunately (wish I didn't have to say it).

The whole setup of Julie running back to the car to show them tells us it's not far at all.
I don't know how far it is. They cut to her showing up at the house, then they cut back to them arriving at the car, with Helen all dressed up. Who knows how much time had passed.
Let's not forget the smell either sea or corpse whatever you like.
Maybe it did smell, but what does that prove exactly? And it didn't really matter anyway, as they all seemed to believe pretty quickly that Julie did see what she said she saw.
I agree the scene is silly, but I guess I'm more forgiving than you since a scene like that is very typical for a teen slasher.

We don't know exactly how far from the road Helen's house is.
The whole setup of Julie running back to the car to show them tells us it's not far at all.
Let's not forget the smell either sea or corpse whatever you like.
It's a pretty ridiculous scene any way you want to take it just there to create some extra thrills for a supposedly non-thinking audience.

she was only gone a couple of minutes
We don't know exactly how far from the road Helen's house is. Julie just stopped the car because she heard a noise in the trunk.
Like the killer is going to clean up the scene in front of traffic in a couple of minutes.
The road didn't seem that busy, but it was indeed a very risky move. I guess he just took his chance when no one was around. The killer removing Max and the crabs was just improvisation anyway, because he would't know if, when or where Julie was going to take a look in the trunk.
but the only way that it makes any sense at all is if you take it as one of Julie's vivid dreams.
My problem with that is still that Julie had no idea Max was dead.

Has to be. It was on a main road in broad daylight and she was only gone a couple of minutes. Like the killer is going to clean up the scene in front of traffic in a couple of minutes. I think it was meant to be real, but the only way that it makes any sense at all is if you take it as one of Julie's vivid dreams.

thats all possible. maybe (SPOILERS BELOW),
just watched part 2 and maybe Ben Willis son helped him clean the trunk out in part 1. two people could do it in time possibly

I doubt it, since she didn't know Max had been killed. It's a stretch, but perhaps he put everything on a piece of tarp so he could put it in and take it out more easily. We also don't know how far from the road Helen's house was, Julie only stopped because she heard a noise. And the killer was probably following her, so when she got out he decided to mess with her mind and remove everything.
It doesn't really make sense, I believe this scene was added later to make it more suspensful.