I think if it's a place you can get to with or without help(i.e. rooftops etc.) it should be allowed with anyone moaning about cheating. They can still be seen and killed.  Now using a glitch in the map is definately cheating. I hate it when someone tries to justify his use of an exploit by saying that anyone can use it.  It's just a lame ass excuse for trying to up you kill/death ratio.  I 've had such bad days playing where I feel like deleteing the entire game from my computer and burning it on the back patio!!!  But, I would not cheat to up my score!
Just my thoughts! 
