Long post is long.
What I say will likely just be an echo of what others before me have said, but I'll just say it anyway. Things like this have likely been discussed by the counsil and among the other admins, many many times. But the final desicion on wether something is an exploit is as follows:
Can they be killed? If a teleporter exit, or other engineer building is built there, can it be destroyed? In other words, can this make the other team, not simply overpowered, but invincable?
There is a line between good but aggrivating, sometimes judged as unfair tactics that are hard to overcome, and providing your team with outright immunity to loss.
I will use 2 examples here, one on both sides of this fence:
The demoman is standing above your spawn in Toyfort, above your bed. He has been reaining down a sticky hell for the past 3 minutes, and its about to cost you the game. It is annoying, however, he is not unkillable. Weapons can be shot up where the stickies are coming from, and soldiers and other demomen can reach him. Make him a priority target, and act accordingly. If you cannot muster enough team coopoeration to kill this solitary target wich has been coiling you in a locker room for that long, your problem is not the demoman, rather, it is your team's innability to combine forces to remove an obstacle. Do what you can as an indivisual to fix this, and hope for the best from there.
Meanwhile in Gravelpit. An engineer has found a hole in the maps floor, allowing him to secretly build under the ground outside his enemy's respawn. His sentry, dispenser, and teleport exits are underground, but can still shoot those on the surface above it. Even if the other team left their spawn with several ubers at once, they can do nothing to stop the engineer's massacre, no matter how skilled they are. He is invincable, and Blu Team wins the game as a result. This is an exploit. Not only is it an exploit, it is greifing, and is something wich should be punished with a swift and final retribution.
These examples clearly have a line carved, the differences are easy to spot and make it very noticable. Other times however, it is not, and so deeper thought must be excersized. So, a third example:
An engineer on Warpath has found a way to get on top of the building above his second point and build there. It is quite obvious that the creators of this map never intendid this, as to get there as that class, you have to jump on what appears to be an invisable platform jutting from the vertical cliff wall. Regardless, he builds there, and his sentry mows down dozens of attackers. So he has done something clearly not meant for this map. But, it is not considered an exploit, and here is why. The building is open, prime sniping territory. A smart sniper from the other team could wipe him out, along with his machines. Soldiers and demomen can hail the building with explosives, well out of range of his sentry. In the end, it is no different than any of the sentry placements anywhere else on the map, perhaps an even worse position than most. In no way does this make his team immune to the other's advance if the team is dedicated to wiping his entrails all over the canyon.
I hope these examples have shown those who were still curious, and provided insight to those that knew but were still unsure. If you run into a situation like the third one, stop and think, ask yourself those three questions.
