1. Not all (and probably not even most) gay guys spit in each others' faces when they have sex. I'm curious about how you would come up with this assertion unless you've been having a lot of gay sex yourself.
2. Some hetereosexual people spit in each others' faces when they have sex---usually it's related to being turned on by sexual humiliation/degredation (roleplaying). People can love each other deeply and still enjoy roleplaying these kinds of scenarios because its a turn-on to both of them.
That's more of a dominance thing than anything else. If my boyfriend ever spat on me I would probably punch him. That's just me though. To each their own. My ex enjoyed being spit on, while I thought it was nasty.
Im gay and I could never have a guy spit on my face or on me in general. To some it could be love and enjoyable and others like myself just wouldn't like it. I find it to be degrading but to each their own. What happens in the bedroom stays there