Conventional thinking is that it would hurt your career. Most porn stars do not cross over into mainstream film and vice versa. THere have been a few exceptions, though. Tracy Lords: Did porn but, because she was under 18, it was all pulled when she revealed her true age. Her mainstream career still hasn't taken off, although she has appeared in a few John Waters movies. Sylvester Stallone: A very early film of his, wayyyy before he became as bulkily muscular as he was for Rocky, was a soft-core porn (Simulated sex acts). And of course, Stallone went on to stardom. Stephen Geoffreys, whom you may remember as Evil from the film "Fright Night" had an OK career in mainstream film up until 1991. Then in 1994 he started making gay porn and hasn't had a mainstream role since.