I think the mental block is that you don't believe that I believe that there are bad referees. Let me put this a different way. I'm goin to categorize the referees and assign a rough percentage to each type of referee based on my years of experience.
Category A (10%): This is a good ref doing a good job that both team think is doing a good job -
(A good referee is one that gets over 95% of the calls right and gets 100% of the major match incidents right). (CLARIFICATION: There are a large amount of calls that can be called either way and still be justified under the laws. A refs "correct" call falls in this allowable range).
Category B (15%): This is a good referee doing a good job that one of the teams think is doing a terrible or subpar job
(The typical reason parents would be mad at a good referee is lack of knowledge of the laws. Other reasons include different styles of soccer or "he made us lose").
Category C (50%): This is an average referee that gets 80-95% of calls right. They usually lack in one way or another aside from knowledge of the game.
(They can fall short slightly in fitness, experience, confidence, or nuance. These are the referees that Bald, surf, and I try to protect. They have potential and are doing the best job they can. They get major calls right, they just need to learn how to "sell" their calls better. Sometimes they give out cards when a better ref could have used his persona. They have trouble dealing with "personalities" and let games get a little wild because of this. They are still getting most calls right. A referee "letting a game get out of control" is usually not lack of foul recognition, but just an inability to assert his authority.
Category D: This is an average referee that misses a major match incident. (5%)
They are told after the game
by their peers because they are open to criticism and feel bad they missed it. It is usually lack of experience or courage/confidence to make the right call that makes them swallow their whistle. Everyone has a bad day occasionally.
Category E: This is a bad referee (15%)
They are either too new or young or old or fat. Maybe they don't have a full grasp of the laws or tunnel vision hard. They still try to be fair and have fun reffing.
Category F: These are (borderline) evil referees. (5%) (probably less though)
Refereeing can attract a certain clientele. These are guys (almost always) whose wives or children or parents don't listen to them at home but now they are the center authority and you have to do what they say. These guys go on a power trip on the field and feed off your helpless whines and tears that are futile because you have to accept their decisions. Be glad that these people only chose refereeing as their outlet to dominate. Unfortunately, they almost never go too far with their power trip to do something that would warrant a revocation of their license. They only never get caught because parents whine too much about Categories B-E.