youngump wroteReally? And what if you're not sure? I doubt you'd really just refuse to make a call on a checked swing. In my mind some calls are best guess if you're not sure, blocked out on a pitch perhaps. And others where you need to be sure, illegal pitch. The key difference usually being that in many cases you have to make some call.
Not sure why you would ask this. I know (several of) your trainers, and know you have been told:
Never guess an out. If you didn't see an out, it must be safe.
Never guess a catch. If you didn't see a catch, it was no catch.
Never guess a strike. If you didn't see a strike, it must be a ball.
Never guess a swing. If you didn't see a swing, it must not have been one.
Never guess a batter out of the box, never guess an illegal pitch, etc, etc.