Actually I have trouble finding a CS server where every player is older than 12, so wish me luck.
Seriously though, that's one thing I hate about CS/CS:S/DoD etc; everyone is so immature. I could moan about it for several paragraphs, but. Actually, I will.
1. Noob-ism
This is probably the funniest one of them all. To be more specific, I laugh like a little girl when I kill someone and they call me a newbie - how the hell did they figure that one out? It's even worse when I occasionally kill the "best" player on the server and he/she calls me a "n00b"...
2. Camping
A viable tactic if used in moderation, IMO. Yesterday morning was the worst scenario of the other team over-using this while using AWM's. Picture this: cs_assault, 8 T's, 5 CT's (myself inclusive), more than half the T's using AWM's camping every (that's 3) entrance to the warehouse. After 35 minutes of standoffs and mass-magnum-rapings, T: 23 CT: 1. IIRC I had 3 kills and somewhere in the region of 20 deaths - I was second place in my team; the guy in 1st had 5 kills and everyone else had 0. Fair play, they defended that place like something they didn't want to loose, but it did get a bit annoying and the insulting reached a record level.
3. AWM Whores
Again, viable in moderation. Obviously it's automatically on the banned list on a lot of servers along with the sheild; after the scenario in #2 you can kind of see why. Personally I've only used this a couple times (usually because I've been assraped 6 ways to sunday and I can't afford it) and found it really easy to get the hang of. I can't see any real way Valve can nerf this, however.
4. The obviously cheating crew
When someone can headshot you through a wall (etc) in a single shot, hit you at absurd distances (headshot in 1 shot again), has a vibrating reticule when you spectate them and seems to anticipate your every move, it becomes obvious they're cheating. I tend to steer clear of non-VAC servers (even though VAC hasn't got much of reputation for being usefull) but I occasionally have to play with / against cheaters, and it's really, really sad. I mean, I'm totally crap at CS, and I've probably bored you to death with all of this (assuming you've bothered to read it this far) but for christs sake I play it using my own hands, eyes and reaction speeds. 'nuff said.
5. The "I'm 12 and l337" crew
Pubeless baby-faced virgins with a skewed mental image of reality, consoling themselves by pretending to be the most mature on the server, instantly giving themselves away by insulting each and every person that kills them. These are the mental rejects of the online gaming community, and I'm fucking glad I'm not one of them.
Well I was trying to think of 7 things but got bored / lost focus. Meh. Maybe I'll finish it later (I'll bet you're looking forward to that).
Laugh at it, change it, cry about it, but please don't insult me over it. My oppinions of what otherwise would be a pretty good game. Tis late now, due to my nature of surfacing at 6:30AM, day in, day out, so I'm off to bed. I may watch a movie first. Wootage.