Reddit is a mess. I used to use all sorts of forums over there, from true crime to gay porn, and very rarely was anyone helpful over there. And for some reason, I kept seeing posts from the notorious "The_Donald" forum despite the fact I never signed up for that. It took me a long time to figure out how to get rid of seeing them. I eventually closed my account.
They do have a forum called "GayPornHunters", but there's all sorts of weird strict rules like all of the thread titles must be in brackets and a certain character amount, or they won't post. Lots of moderators who run their forums like dictators and others who have disappeared and their forums have turn into troll wastelands. There is one user at GayPornHunters that is very knowledgeable -- I think his username is "mmoonnkkeeyy" or something like that. Maybe seek him out if you're going to use it.
Were you looking more for porn identification help or help tracking down certain scenes?