Yes, I agree that playing defensively is a good, smart playstyle, but finding a hiding spot off the spawn and waiting for people to pass by you is just plain ol' dumb.
I was recently playing on the amazing server that is Aloha Last Team Standing, where you don't respawn and the team that eliminates all the enemies wins. Unfortunately, the other team was playing, in my opinion, in a very dishonest way. As soon as the timer went down and they were able to get out of spawn, almost all of them set up camp in the pit below them, and aimed towards the only direction the other team could come from. Why on earth would someone do this? No, I'm not mad because I got outplayed. In fact, I had exactly 5.8 times more kills than the best camper on their team, in the same amount of time. I find it insulting that I learned to play the game correctly.