From what I have seen, Call of Duty multiplayer is filled with cheating throughout. I've seen literally hundreds of gameplay videos on youtube for just average people playing call of duty, and everyone is running around quickscoping everyone in the head for instant sniper kills. Lots of people flying and using aimbots too. Its practically impossible to miss.
Not to mention if you get hit by a bullet you usually die in one shot. Total bullcrap. What is this supposed to be, real life? Totally defeats the purpose of playing video games.
This is why I stick to TF2. Give me a bottle of water, a comfy chair, the computer, and several hours on the Intox Zombie Fortress server and I am set.