Snipers don't have to camp. Sometimes it's even better if they don't. Snipers, especially on big maps, can take a shot from anywhere then move to another spot and get another kill without risking a guy going up to them after they've been killed (killcam in CoD's). It gives you more angles as well. Oh and occasionally you can get a "free" kill when someone goes up to your previous location and you can give them a little surprise. I personally "camp" (I move a around in a spot but generally stay in a certain area) only while sniping or on defense.