The Team Fortress 2 Blog has a post that recalls the recent TF 2 Soldier/Demoman war, noting the stats suggest some cheating may have taken place. They offer the stats and the following analysis:

Now, I have no actual proof that these men cheated. Lucky for me, then, that I am still in possession of basic common bloody sense. The top Soldier, for example, would have had to kill a Demoman every 2.5 seconds for a week straight, somehow circumventing respawn timers or the need to actually traverse across a map, without once pausing to sleep or go to the bathroom. In other words, he is either cheating, or he is a hallucinating sleep-deprived psychotic with severe constipation and unerringly good aim. In either event, I am confident he is ashamed of himself.