Over the years I received many calls from coaches complaining about a "bad call". If it's about a misapplied rule, I'll listen. If it's about a judgement call, I'll politely respond : "Coach, he called it with what he saw through his eyes, not what was seen through the video." Oddly enough the judgement calls on fouls are from 90% flags thrown that shouldn't have been to 10% on flags that should have been that weren't.
MORALE OF STORY : When not sure, DON'T throw the flag.