Right on!
Grease
is a prime example.

True! Just look at Grease!
If we take the time to see with the heart and not with the mind, we shall see that we are surrounded completely by angels ~ Carlos Santana

My impressions probably stem from the fact that I watched it on Tubi.com, which shows everything in near-High def picture quality, and Clayton's face (as well as a few of the others) definitely shows its age with that kind of sharpness. It didn't bother me too much, though… you see a lot of "older" actors/actresses being cast in teenage roles - it's just the way the movie biz operates.

Looking back, he did have a young looking face
If we take the time to see with the heart and not with the mind, we shall see that we are surrounded completely by angels ~ Carlos Santana

Miscast only in the sense that at 28, he was way too old to be playing an awkward teenage high schooler (BTW, he was 28… but then again, Joyce Hyser (Terri), then 27, also struck me as too old for a high schooler). I thought he turned in a good performance, but every time he was on camera the thought kept hitting me that he was too old for the part.
I thought that at the end, during the prom, he looked like Val Kilmer & Jim Carey morphed into one.

I thought he was great, granted he didn't look like a highschooler.

Disagree.he played a perfect doucher.
Whose idea was it for the word "Lisp" to have an "S" in it?

Disagree - not sure how he could've fit any better. He did a great job for the film.

Disagree
He was great. Did he look like a teenager? Not even close but he worked for that character