Well first of all, pretty much almost EVERYONE at a con looks like a nerdy 40yo virgin, or worse. It's the last bastion of the classic unwashed fat neckbeard in society. But the good part is that they're less self-conscious about it, since so many of them look like (and in fact are) misshapen autists, so it actually helps these people attain self-acceptance and crack the malignant shell of insecurity that they've been residing in since who knows when. Human looks matter much less when you know that the ugliest smelliest fuck at the con can always put on a beautiful suit and make those superficial qualities vanish if only for a limited time. But you don't need a suit of your own to reap the rewards of this arrangement either.
I can only speak for european cons (From what I could see, american cons are much more degenerate on average), but you are unlikely to come across lewdness unless you actively seek it out. Either way, don't expect to get laid as a hetero even if you try, gays on the other hand… Room orgies do supposedly happen on occasion, but 90% of any given con will be spent with you observing, hugging and petting random strangers in suits, and going to workshops and presentations (if you're new) or spending time with your con buddies (if you're old). It's a good place to network at, to the point where it's almost like an autistic version of a freemason lodge.