*First off I put this in the COD forum purely because COD was the game I was playing while thinking about these questions but are not specific to the franchise (or even genre in some cases). Just for reference I'm not a fan boy or hater so don't just post crap about COD or BF being better than one and other etc as there's plenty of other post for that.*

While playing most FPS online I always come across at least one person who loves camping. They go to the same place every time they re-spawn and just sit facing the doorway. My question is why? What enjoyment do  you get out of this experience? It's not exclusive to "noobs" either, I see guys on their multiple prestige pulling the same thing. I decided to give it a go and find out...I lasted 2 mins before I was bored rigid. I'm not complaining as hell I'll take an easy grenade kill while passing as readily as the next guy but it does leave me curious. Are you a camper? If so what makes you use that particular play style? Ive also noticed that most of the time their K/D ratio is horrible (in a negative way) so I can asume it's not for XP gain. It's not my play style and I'm not going to fault you for it but I just don't get it. 
 
PS, not really including snipers as much in this but feel free to throw in your views.

If you camp for long enough you will get kills. But its a matter of seconds until you die after the first kill unless the other team is completely idiotic. Thats camping a doorway anyways.

You can also consider running up and down one side of the map camping, and thats extremely effective, but way more involved than just watching a doorway. Thats really how your supposed to play most modern FPS games, I never do it because its boring.

I hate campers, when playing those games I like to keep on moving, I may pass by the place where enimies spawn but I won't stay there.

i just run forward until i'm dead, sometimes taking someone else down with me

I don't see the problem people have with "campers" if they're always in the same fucking spot, toss a grenade in there and kill him.

The rage that you hear through the mic as the SAME guy dies 10 times in the SAME spot that I have decided to camp in is sweet music to my ears, all day, every day.

I've never understood it myself either. I honestly don't care about my K/D ratio as much as I do my fun ratio. Sitting in the corner the whole match pointing my gun at the door isn't what I paid $60 to experience.

If I feel like being annoying I will camp. 
On Convoy for Black Ops (S&D) I sat in the diner the entire game because I was doing something else at the time and I ended up with 14-0 as my score.
5 seconds after the game someone sends me a message "FUCKIN CAMPER!" I sent him a message saying "Yo dawg, I'm MLG" 
 
Greatest game of my time in CoD.

@TanoPrime: I can see why that would work if they are dumb enough to keep running into the same room. I bet that level of stupidity happens quite a bit with some people. You may get me once or twice but either I'll nade the shit out of that room or let someone else go in first :) But you are right about people who scream about campers but keep doing the same thing again and again without figuring out its not the best way to approach the situation.

Killstreaks are just one of the many reasons why camping is the best strategy in CoD
 
Also I play Search which is the best mode for rage and I camp in Blops but in MW2 I used to play Shee Roller with my buddies and we'd all go riot shield and throwing knives with scavenger and oh boy I have some fucking great memories from that. MW2 owns.

I was a camper when I was playing CoD 4 & WaW, but I did throw some run and gun in to mix things up every so often.. One thing that always bothered me was when people would complain that camping takes no skill. Camping requires a lot of patience and situational awareness. It requires you to be aware of all entrances, walls that can be shot through, windows that make you visible to snipers, and to know the prime spots on each map (which in turn requires you to know each map in detail). So yeah, while that play style might not require the quickdraw skill of a run and gunner, it does take strategic skill to do properly. And to me that is fun.