I've been playing COD4 and COD:MW2 for ages now, and I've had enough. It's time to let go of these games, whose extremely limited single-player content and their frustrating, immature multiplayer act as vast impediments to what could otherwise have been extremely good games. They are both brilliant visually and technically, but, unfortunately, there is simply no sense at all in the multiplayer, which is the selling point of the game.
Before anyone argues with me on that, I consider a good multiplayer one that is fun. I played some Cagematch on CoD4 and realized how how much it stops short of being fun. A cagematch is a one on one fight. It's not hard to find a match that doesn't lag, and even if you're not hosting, you're not at much of a disadvantage. The problem is that the game is exploitable in so many ways. Low health and killstreaks encourage camping, and there's nothing you can do if the camper keeps switching locations. You can't even see the camper until it's too late, or not all if they're sniping from a distance. Not only that, but cheap tactics like throwing grenades at one's feet to kill oneself when under fire continue to make the match frustrating and pointless. The final exploitable thing is the spawn system. Experienced players simply know where their opponent is going to spawn and so cover that area from a distance where it is almost impossible to see them. It takes a few deaths to finally dislodge them, but a few deaths is probably a win for them. A spawn system should spawn you as far away from the opponent as possible, not give you up neatly wrapped to your opponent. It would be stupid to be optimistic and hope that the game's flaws won't be exploited, because the internet community very rarely behave in a sportsmanlike way.
I don't use these tactics because they're neither fair nor fun for me, therefore I will ditch the fiasco of a franchise that is Call of Duty, until it occurs to some developer to make the game fun.