For players who just refuse to learn how to play, and will stick to their camping roots, I see those players using light rifles - pop you from long range with a light rifle, switch to secondary to finish you off.
I consider camping f.e. Hiding in a specific house or hallway.
You guys got that stuff cleared up mostly; I just wanted to add: A house can offer quite a lot of corners/hiding spots. That's what a "skilled" camper would make much use of.