I've been to a number of swingers clubs and you get the complete spectrum of humanity in them.
A couple of clubs are a bit seedy / run down, but most aim for a more "professional" image.
Sure, you do get the middle aged pit-bellied guys, but in my experience, they tend to be in a couple, not usually single. You also get larger women, again usually in a couple.
KK may be seen as "elitist", but so what? In my personal experience, being a (trim, fit and not completely ugly - just so you know) guy nearly 60, I found I was ignored, but that's ok - each to their own - I didn't take it personally - and I think that's key for anyone considering a journey into "the dark side".
As for older "ugly" fatter men looking for younger, slimmer, more attractive women - you don't think that older, fatter, unattractive women are looking for taller, slimmer, younger, more attractive men? Grow up. We all fantasise about the unobtainable. I guarantee you have a celeb you crush on.
IMHO, there is definitely a difference between casual sex & swinging. Casual sex can be a temporary thing. Swinging is a lifestyle choice (not just for Christmas!
).
Of course there will be 99 people out of 100 that you aren't interested in playing with, and no-one will condemn you for having standards, but you generally meet lots of interesting and really nice people, who all have an open and honest approach to sex, and can end up being very close friends. When the starts do align, you can end up having something very special.