Another kind of cheating would involve "home team" biases, where the host club tries to get a leg up on the competing clubs in a rivalry by losing an entry here and there.
Mostly, though, I would think cheating involves knowing which beers belong to which brewer. This is the reason for anonymity in bottle shape and size and blacking out marks on the caps.
I suppose a dishonest steward could influence the outcome, but I've never seen that. Actually I've seen people request to be stewards on flights they have an entry. This should be discouraged unless that person is beyond reproach.