Gay bottoms take notice -- A lot of guys have wanted to give you a clue on this, and now here is a perfect opportunity. When you're at the baths or a sex party (not that I've been to those, LOL) don't immediately bend over and show your hole. That is a turn off to a lot of Tops. Plus it destroys the gorgeous natural curve of the butt which might be what attracted him to you in the first place. Let him play with your butt cheeks awhile. THEN, when he is really turned on and ready to fuck, then the site of your butthole will further inflame his lust instead of killing it. As with many things in life, timing is everything. I'm not claiming all gay Tops feel this way, but MANY of them do. Just putting it out there for what it's worth because it's obvious it hasn't ever occurred to some people.
One of my favorite picture sharing groups was just butt shots with a firm rule about no anal. Unless you are on the verge of fucking, the site of a butthole is often not a turn-on. (However, if I am about to fuck you and you show me the target, it's a bigger turn on if it's hairy. LOL)
*And before those who don't feel this way jump all over me, it's not just me who feels this way. I've had this discussion with friends as well as with strangers in a group situation.