I would say that it is almost impossible for a straight guy to score a gay guy, unless you are very very good looking and got all your fashion shit together.
Don't flatter yourself.
An average gay male will be having sex with somewhere from 1,000 to 10,000 different partners in his lifetime (i.e. before he dies from HIV/AIDS or Syphilis). May be 1% or 2% out of that will be good looking. That said, why should a straight guy try to score a gay guy? For getting HIV?
LMFAO, unless you're going with the "you've had sex with everyone you've had sex with has ever had sex with to infinity"...