I have a couple things to add:
(Disclaimer: I only read the first page, and the 6th page, so if my points were already made in the pages in between those, i apologize.)
First, a story. This happened over the last two days. To start, I had just downloaded Synergy on Steam the previous day, and I noticed my friend was playing it, so i joined his game. When I got there, there were 8-10 people on the server, and they were doing the last strider battle of Episode 2. Not too bad, except everybody but a few people were just screwing off (taking the cars and hiding them, hogging the dispensers, etc). In particular, there was this one kid (probably about 3 years old, swears a lot) who kept insisting that he was killing all the striders, even when i had personally done it:
another person- "good job!"
me- "tha-"
idiot- "THAT WAS TOTALLY ME, IVE BEEN DOING ALL THE WORK FOR YOU IDIOTS AND YOU DONT EVEN CARE"
and later
me- "hey *DELETED*, were having some trouble killing these things, why dont you give us a hand and show off your 'leetness' (yes i actually said that)?"
him- "NO"
me- "Why?"
him- "I died!"
me- ???
him- "I DIED SO IM NOT HELPING YOU GUYS ANY MORE!"
me- ...
not long after that
me- *kills strider*
him- "THAT WAS TOTALLY ME"
me- "Thought you weren't helping any more?"
him- "Yeah, i changed my mind"
me- *disconnects*
On the other side of the coin, however, the next day (yesterday) i joined a server that was in the canals of Half-Life 2. There i met some really great people, one of them had a really high-pitched voice. That annoyed me at first, causing me to ignore him out of habit. Throughout the game, especially during Ravenholm, i noticed that he was actually a really good player. He didn't talk much, and i had more of a problem understanding him because of the fact that his mic sucked and he was way too quiet, than the fact that he had a high voice.
Oh, I also went onto another server on Synergy that was on the prison levels. There were 6-8 people on the level, saying that they had to conserve their ammo, so they all grabbed something with the physics gun to use as a shield/projectile, flinging those at zombies and combine (and they wondered why they were lagging! 8 people each using a physics object, go figure!), yet they were using AR2 ammo on headcrabs. I left shortly after i joined.
Last note is that I don't meet many high-pitched, whiny, sweary 3 year olds on TF2. I find most of the people on TF2 to be fairly mature, maybe unpracticed at the game, but generally polite, not using the mic for music (except once, he got kicked fast) and stuff. Maybe i just found a good few servers, not sure.
Very poorly formatted post, sorry. I'm tired, first day of school after break, etc.