Incontrovertible, Socratic proof for anyone anywhere who still doubts that Xander could possibly ever be gay:
Universal given: All sex with Faith, no matter the gender, species, or number of the other participants, is by Faith's very nature, gay.
Canon fact: Xander has had sex with Faith.
Ergo: Xander is gay.
Thank you and good night.
P.S. Obviously, this works for Robin Wood as well, but with those eyelashes, was there ever any doubt? Wesley, on the other hand, has had no textual sex with Faith, so sorry folks, he's not gay, he's just British.