As you may or may not have heard, people have developed programs that would simulate you being in a server ‘idling’. You would just leave it on overnight, then in the morning, wake up to loads of goodies in your inventory.
Not anymore, since Valve is now catching on to players who decide to do this. They are removing all the items that were achieved through illegitimate means and giving everyone else who didn’t cheat a free hat!
If you still decide to use external applications, then Valve will take all your items away.
TF2 Blog [Valve]
