They way I see it, style is about exaggerating proportions and what symbols one uses. As long as you follow the rules you've set consistently and follow anatomy, you can tweak proportions and have it look okay. (With a few exceptions, like Olive Oyl limbs and superheroine swivel-chair spine syndrome.) My question is, just how far can you take these proportions before it stops being stylized and becomes bad art? What is the difference between accepted stylizing (Adventure Time, The World Ends With You, Avatar (both series)) and unacceptable stylizing (not going to name names here)?
Edit: Sorry, I should have been a bit more specific. I mean style in character design.