I do not know if COD4 got a moderator or admin on when this happens.
But on the COD 5 freeze tag we nearly always have a moderator and some admins playing.
We at COD5 freezetag had some similar issues about a year ago, accusations getting out of hand. Up to the point where some regular players started to stay away from the game just because of this.
So we , the moderators, admins and head admins started posting this message whenever we heard accusations of cheating or hacking. WARNING: allegations of cheating without proof are grounds for kick/ban
If the same person who kept accusing persisted we kicked.
and guess what, those accusations dropped real fast; now i have to admit, we normally always play with the same group of people, but if new people come in and start accusing , up comes the text and it works.
And yes, we get the occasional BS but i always reply that it really was the Best Shot.