MW2 is fine, I just mute people the second they start to become annoying.

Killzone 2 online is also great, very little problems there.

Fifa is a bit annoying in that players love to leave at the last second if they are losing as you mentioned.

Xbox Live is pretty much the same, except replace the chaps speaking in french/spanish/german with more howling american teens.

i very rarly come across people like.. the last time i played with someone like that my friend was there and this kid was really pissing him of so he grab my head set and started threating him then the kid left I ROFL'd...

then Live should have been doomez ages ago...it's way worse so no

There are standard features in Live that help though: you can limit audio to friends only, so that you never have to hear the randoms, you can avoid players so you never have to play with them again, and if they are glitchers, you can report them - with enough reports = player ban.

That being said, the anonymity of the interwebz allows the inner jackass in a lot of people to come out, but it isnt just limited to the PSN though.  IT is on Live as well and hell there are people on VGChartz who respond in posts in such a way that they would never do if they were looking someone else in the eye...

What's the consequence from that?

I think that people who hates others talking in other languages is also a major part of why online multiplayer sucks :P

The community are alright for the most part. RD: R though, co-op especially- is full of useless players and quitters. It's so rare to get a game with 3 people who know what they're doing and don't quit in a tantrum.

Most of those problems are from game design, a lot of developers don't know how to design multiplayer systems properly to prevent things like that.  People will always be stat whores, min/max, cheat, hack, or whatever to gain an advantage.  The only way to properly prevent that is to tie account creation with hard ids like credit cards, names, or console ids and once perma banned do not allow another account to be created off of those identifiers.  Having good admins and being able to report players is also a big plus.  Unfortunately a lot of game devs will just release then let the multiplayer to rot because they've already made their money and they don't care anymore.

Also playing with friends and clanmates is the way to go.  Not only do you not have to hear the prepubescent jackasses all day, but you get to own them too since teamwork is usually nonexistant on pubs.

Let's say I'm winning 15-0. If he leaves at the very last minute, it will automatically end 3-0 for me. Plus it's annoying when you're  playing really well and the other guy just leaves.

This is not new at all, both PSN an XBL are filled with annoying people. DAH. It gives people a safe place to say what is not socially acceptable in real life. Things that actually could have repercussions in real life. So no the community is not doomed, and the assholes on both of these networks is not suprising at all.