I think actually this case has a quite realistic look. There are no model-material actors in it - Finn and Archie are alright, Chloe looks like a lot of teenage girls (and that's necessary because it has a bit of an influence over her relationship with Rae), the other girl I forget the name of is average, Chop is below average (though I expect some people find him attractive because there is perhaps something about him....). There's a good variety - no HIDEOUS cast members, no unrealistically good looking ones either. Which is good when the show is partly about the physical aspects of people.
I agree, i think they all look like "normal" teenagers.