If the calls are so subjective that one can't tell the difference between a ref accidentally being way off and on purpose being way off, then maybe your sport/rules are the problem when being way off is either excusable or indeterminable. (in the NBA and some other sports, you can basically call a foul every play)
I would propose doing away with refs entirely, like in Ultimate Frisbee. This would entail pretty radical changes to professional sports, but why not. At the highest level of play (and pay), contestants should be able to fiercely compete under principles of fairness and cooperation instead of establishing the current culture of flopping, doping and "off the field issues".
This would turn every professional sport into the UFC.