Just looks

Today i am full of questions, maybe that's a good thing, maybe the route to success is full of unanswered questions.. god, i do hope so!

The question may seem shallow but i think it is of more importance than it may sound:
Does the female protagonist need to be beautiful or can a character afford to be mediocre looking when her character is likeable? Should you let the readers know at all how anyone looks? Are they offended when the author describes the character in some way other than they imagined?

Now, in movies the most beautiful people often aren't the ones you fall in love with. Being not ugly surely does help but most of the times attractiveness doesn't mean a thing when the character in itself is flat.

Maybe there's a way out of the crisis. When creating a character for a story, being pretty doesn't hurt if the character herself is self-conscious about her appearance. People can identify with that, don't they? Being more critical about oneself than necessary seems to be a common thing.

But there's a fine line between "she's pretty but has low self esteem" and "she's pretty and fishes for compliments". At least i don't know how to create either of these traits. Plus the first one may not appear as logical to the reader. Maybe the protagonist needs some sort of impairment to convince the reader that she really doesn't think of herself as beautiful. After all, it's a question of credibility. An eating disorder seems to be the obvious choice but what about social anxiety? Too much of a cliche?