My suggestion is that it's kind of like racism. I personally reject racism because I'd rather take the effort to hate people as individuals instead. 🙂
The reason you see them as clones is that while they may share some characteristics, you have yet to examine them closely enough to discern the differences. I suspect that a little conversation could be just as helpful as genetic testing to expose them as distinct, unique individuals, and not clones. Of course, they may be interchangeable in many areas, but I would consider it shallow to think of them as all the same.
You will find the same sort of thing in many other environments, including, for example, sports bars, where the majority of the patrons are supporting the same team, often wearing the same team colours and uniforms, chanting the same slogans, and cheering in unison, as if they were synchronized robotic automatons.
As far as "What's wrong with a regular bar", in many of them, you could be putting your life in danger if you kiss another fellow, or even do something as explicit as holding hands, or looking at each other the "wrong" way. Some people find it enjoyable to be able to relax, and act on their feelings without having to self-censor every action, thought, and deed.
Oh, and that uninhibited sex behind a building may be interpreted by law enforcement types as lewd conduct in a public area, which has the potential of getting you confined in a locked room (with walls, or bars), and they may not be terribly quick to react should some of the other people in said locked room choose to act in an uninhibited way that may or not have your consent.