Well, Bulldog and Niles and Gil (the restaurant critic) are homos IRL.
Frasier also had a one-off episode "Good Samaritan" that centered around a trans prostitute, who is then corn-ily discovered not to be a pro but a resident of his same building. Also, Frasier's boss Mercedes Ruehl is all woman, but one would swear the producers told her to play the role as a trans.
I would think Jane Leeves in her prime would have made a gay man straight. You should have seen her when she was on The Benny Hill Show.
Bulldog?
The father is. Mahoney. An old homo.