A woman can be a good porn star with an average-slightly above average face. All she needs is a great body and a willingness to look like she's having fun on film.
In my opinion, there are no truly great porn stars who don't have beautiful faces. There are some who may be memorable for other reasons, but to be one of the great ones, they have to have a beautiful face as well as a great body and personality.
Breasts aren't that big of a deal to me. After thinking about it, I've decided I must be an ass man. Yeah, people come up to me all the time and tell me "you're an ASS, man!" :1orglaugh