For MW2, (it always comes up doesnt it)there seems to be debate about having any kind of tactic atall. If you stop, you're camping - death to campers!
If you really are such a twirp that you grab yourself marathon, lightweight and commando and charge around the map knifing people, you are a marathon, lightweight and commando twirp and everyone hates you.
If you even think about attaching a heartbeat sensor to your gun in order to locate campers/lightweight twirps you are heartbeat noob.
Oh and i nearly forgot, if you dare use a grenade launcher to clean out a room of campers in say, Headquarters, well, how dare you kill us you noob tuber, you really must somehow creep up to the room, gradually pick off the room's inhabitants without anyone else noticing you, quickly, so they dont capture the objective.
Oh wait no, sub machine gun/ shotgun noober, quickly killing off a room with a rapid fire weapon.
Oh, by the way no thermal scope on your sniper rifle that's cheating too...
So, that leaves, a very gentlemenly game where everyone lines up with the FAL single shot assault rifle, and fires into the opposing team. No moving, no grenades, no flashbangs, no riot sheild obviously that seems to baffle people who refuse to use grenades only guns. For a game with so many varying tactics and possibilites its surprising everyone really wants a game from the American revolutionary war.