How do people with "specific interests" meet each other?

I'm just gonna be blunt here cuz it's so much harder to explain trying to dance around the subject. Is there a dating route that accounts for ones more deviant interests? Like, how do people into Roleplay, cosplay, exhibitionism, CNC, BDSM, the gross ones, etc meet each other? For that matter, what about matching general levels of horniness/sex drives? I'm aware that relationships are generally a give and take and what not but I'm just curious if these people just kinda have to deal with dating being a harder endeavor than it already is