[Cliche]

The thing is, is that on some jungle maps, unless the sniper is following the shoot and move tactic (which 90% don't follow) it's usually 1 or 2 kills before counter-sniping actions are taken. Also with all of the sniper rifles tracers, it's pretty difficult to stay in one cubby-hole for too long. Also as maps become more well known and practiced, the usual sniping positions are given away and the game changes once again.

Also most of the awful snipers don't bother to switch to their pistols every now and then to take a look at their surroundings, making them easy knife meat.