I've coached for a while now and seen umpiring of pretty much every level and at every district stadium in Adelaide.
I think you guys are being quite harsh in your comments and I personally can only think of 4 or 5 occasions when I feel a referee has deliberately done the wrong thing or favoured one team over the other.
I also would think that 'cheating' would actually require a lot more talent than most junior referees have. I would think most if not all referees make calls on impulse and wouldn't have the ability to change that impulse.
Now maybe if a certain team's parents, coach or players were giving that referee a hard time then subconsciously that referee might make 1 or 2 calls against them, but on the other side they might have 1 or 2 go in that teams favour to try and shut them up. I'm not saying they do that on purpose but we're all human and I would think it would be natural for an umpire to respond in some way to being yelled at.
I also think that because some refs seem to stay at the same stadiums that there is a sense of familiarity both from players and coaches as well as from the referee.
A coach might get the same ref every second week and learn that he/she calls lots of travels or lots of hands fouls and therefore instruct their team to be particularly careful. Then that team gets no travels called against them but the visiting team gets plenty, visiting team's response is that the ref is a cheat.
On the other side refs might get the same teams/coaches often and then get a feel for how that team plays. If a ref does a certain grade every second week and the home team always plays physical they might then let a lot of contact go. Home team continues to be physical, away team plays clean and can't understand how the home team can be so rough; refs must be cheating.
I also question the level of education people get. As a coach I've never been taught the rules, or had someone explain the interpretations to me unless I asked, and even then you get varying responses. I certainly don't know of any rules courses for parents/players. I assume that referees in different stadiums would be getting taught by different people and therefore would be getting different feedback as to how to read a game and let a game flow.
There are so many variables and I think calling a referee a cheat is a simple way to deal with something you as a coach, parent or player don't agree with but I certainly don't think that its a very accurate conclusion.
That's my two cents anyway!