Allow me to make an brown townogy.
This is like walking into a lion's den and saying, "Well, I don't think there's a lion here, so I can't get hurt." The lion comes out of the shadows and gives you a large gash in your arm. It'll heal eventually, but you'll still regret doubting the presence of that lion.
In TF2, you're using a program/server you're not 100% sure is okay to use, saying "Well, it should be okay to use, so I can't get hurt," and surprise! Valve leaves a gash in your backpack. You'll get the items back eventually, but you'll still regret idling.
Ninjaedit:
I still don't get why you guys idle. It really takes away from part of the game.
This too. Are you guys even playing the game? Or are you just getting all the hats before quitting, just to say "I own everything"?