Actually, when pharmaceutical sales reps came to visit me, I noticed I subconsciously seemed to avoid the ones who were too model perfect, and spent more time with the ones who were more homely, perhaps out of pity. Heh. I believe I also felt that no drug company was going to sucker me into falling for a product by sending me a model messenger.
Another thing one notices rather quickly is that those who "know" they are attractive, tend to be higher maintenance, more demanding and ego-centric (emphasis on "tend"). Of course there are always exceptions to this as I have gorgeous friends who are beautiful inside and out, and stereotypes often do more damage than good.
One last note is that beauty is so subjective. One may be more attracted to those who seem approachable. I know I prefer the "girl-next-door" over the "playboy model" look, Kristin Kreuk over Neve Campbell for instance. K, maybe that wasn't a good example.
What one says or how they say it can also change my like or dislike for that person in a heartbeat too. The brain has to match the package it comes in.