I play Search and Destroy nearly exclusively, so to me it's acceptable to stay in one spot the entire round if you're covering a bombsite and know that the other bombsite is being guarded by teammates. Of course this is different when you're on the attacking team, in which case I don't mind the other team staying tight to the bombsite. I still find it ridiculous that people will complain about not running after a dropped bomb when it's clearly being covered by 2 or 3 enemies, though, when I sneak around to try and find an advantage against them.
If you're sat in an obtuse corner of the map where you're not contributing to the game it's camping. If you're in a good spot where you know you'll encounter enemies and helping win the objective it's fine by me. Don't move an inch if you don't want to.
I got an abuse message on Favela a few days ago because I was playing Hardcore Headquarters and found a nice little spot overlooking an alley where I knew the enemy would funnel down. My team were attacking the HQ location, so as I did that I stuck to that spot and held off the enemies as they managed to capture the HQ, and then killed enough guys from that spot to prevent them from destroying it. Still people were branding me a lame camper because I happened to have a good tactical position and wasn't stupid enough to leave it.
I realise that most people in this thread will see it as camping but in my mind it's fine because I'm killing enemies and helping my team. In a way I'm glad a lot of people are against "camping" and run around like headless chickens, though, because they're the easiest kills in the game. Nothing like some idiot running towards my position for the fourth time madly firing a SPAS and not getting near me. :lol