I think you forget some cases like :
- I'm single and a shitload of kilometers away from my main social life
- I'm single and on a work trip
- I'm in a couple and we have got an agreement (ok this one is more of a fantasm ... not mine but anyway, that happens)
And the fact that this is totaly different from the relations you have with your girlfriend/wife.
You don't look for the same things, at all.
I'm speaking about my case, I have just done only two walks up, but the fun for me is going into a place I don't know, like a child who knows he's doing something ''bad'' and people in the street don't know that ... it's not even the sex (ok I might definitely be too newby to compare on that point, but still the idea is there).
It's also because I come from a country where going to the WG is not the norm, it's not common. So I wanted to discover that, because I wanted to discover that by myself, in a way not to die stupid (not sure if that expression makes sense in english ...).
But yeah, it's expensive. I'm happy in a way because I know I'm not staying eternaly in HK so I will be off before bankruptcy.
And for the chances of getting diseases, the only girl who wanted to do uncovered sex with me lightly was an american girlfriend here, not a chinese WG ...
But anyway yeah, of course it would be stupid to ruin a healthy relation because of mongering.
Luckily I'm not concerned