Chess.com is probably the best place I've seen concerning this. I don't see how you could change for the better. You'll always get a chance of playing a moron, but it's far from being the majority of players.
Chess.com and bad players

I just decided that during games, I'm here to play chess and not chat. So I disable chat during all games unless I'm playing with a friend. I was tired of the insults, pressure to resign or the odd way they always asked questions when it was my move (an obvious ploy to run my clock typing rather than playing).

I mainly play online chess and I don't ever remember seeing abusive comments. Of course you're not on such a strict time schedule so it's easier to block them if that happens.

chess.com is the best I have tried most all I think. Savor the good games and forget the bad. At least at chess.com they are pretty on top of cheating, a huge concern on sites like yahoo or others. ICC the competition is rigid and certain reply's to openings have an almost cult following. Destroyers on here annoy me most but I am learning how to shut these types down as they are predictable if nothing else. Have you tried joining groups? you can often meet people within your team to "train" with. as for the insulting draw requesting patzers.. just win.. gl

Yeah sometimes there are annoying people out their but what really annoys be is when you play 30 min standard chess on live chess and your opponent just keeps saying "lets go lets go lets go lets go
Your too slow blah blah, IT'S 30 MIN CHESS FOR CRYING OUTLOUD but guess what happens next? They blunder and end up losing to me :)

I am so disappointed by many players, disconnecting, insulting you, making no moves or just destroyers with no game strategy. Is that the result of free chess?
I am looking to change chess internet provider but where to go? I would not mind paying a little to get rid of those waste of time and bothering players.
How chess.com could prevent such behavior? Because apparently restriction doesn't help. Ok you will say that is why you have the option to add friends but then you just play with limited number of opponents when they are available...
You can block them.

In over 1100 on line games at chess.com, I've run into only one really rude opponent. Maybe I've been lucky, but it seems to me that the majority of players respect each other. Chess.com has provided many tools to deal with rudeness (including reporting them if it really gets bad). I would suggest you hang in there and hopefully your experiences will get better.
I am so disappointed by many players, disconnecting, insulting you, making no moves or just destroyers with no game strategy. Is that the result of free chess?
I am looking to change chess internet provider but where to go? I would not mind paying a little to get rid of those waste of time and bothering players.
How chess.com could prevent such behavior? Because apparently restriction doesn't help. Ok you will say that is why you have the option to add friends but then you just play with limited number of opponents when they are available...