I had one of those "crazies" last year try out again this year - she missed curfew at Nationals, her mom was swearing and screaming at me the day they were set to compete, and as soon as we were back in AZ she got a small group of moms to go with her to the AD (and then principal when the AD did nothing...and then district AD when the principal did nothing...then district superintendent when the district AD did nothing) to try and get me fired by claiming "emotional abuse, harassment, favoritism, and embezzling funds (my favorite claim since I touch absolutely no money and it all goes in the bookstore so it's literally impossible to embezzle)". Obviously all the other girls and parents defended me and debunked those pretty quickly, but when it came time for tryouts, I knew I had to be completely separated from the process because if she got cut (which ended up happening because she had no tumbling and her stunting was average), I could honestly say it was an impartial set of judges who scored her skills, and then her grades/teacher recommendations as well.
One thing I do add to their 100-point scoresheet is 15 points for "coachability" though. This is essentially my way of having some input on who makes it and who doesn't without actually judging the tryout. The key is that I fill in their coachability score without looking at what the judges put for everything else. It's 100% blind, but it gives me the ability to kind of 'sway' the girls who may not have as much talent but are hardworking, willing to put in the time, have great attitudes, etc. and give them extra points, while docking the ones who just cheer to be a cheerleader and for no other reason. If I give a boy/girl a low score and they still are above the cut line, then I'll still take them and work with them about their attitude, then kick them off if need be. Same goes for the reverse - if I give them high coachability but the judges gave them a really low score and they miss the cutoff, I can't do anything about it. I like to think I'm pretty fair about this score though - even with the girl I mentioned above I still gave her an 8/15, and I only gave one girl a 15/15, so it's not going to completely overshadow the actual talent/grades/recommendations portion of the scoresheet.
Another extremely long post by me, sorry that I write novels.