My wife is a rep (and has been for 13 years), and while I would agree that a majority of the reps are fairly attractive, I wouldn't go as far as some here have. She has a target list of doctors to see, and a majority of them are willing to listen for a few minutes and then sign for their samples. I think what products you are selling has a lot to do with it.
It seems like all the big companies are downsizing their sales force right now, so it may be a tough door to get in. It might be easier to try to find a smaller company and get in with them.
has some listings.