When is "open minded" a not compliment, and when is it a compliment?

when it isn’t true.

It IS a compliment when it means you (or someone) is reasonable enough to understand the intention of a law, rule, or belief—but that in the spirit of the same belief, there may be an exception. For instance, I remember once telling a seventeen-year-old that I would NEVER normally advocate lying—but in the particular instance we were dealing with then, telling the truth would be used as ammo against an innocent person. There was actually nothing wrong done but telling the truth would be made into that.

An open minded person might make an exception that someone might steal food to eat and survive. Or may have a medical condition. Or, maybe the wrong parent is NOT where a child should be, even if the law specifies.

I don’t know when open minded WOULDN’T be used as a compliment unless it was meant someone who wouldn’t stick to ANY rule and would believe ANY lie. That would mean TOO open minded. For instance, if there were puddles and wet buildings outside and people were carrying umbrellas you might deduct that it rained. But a person who is TOO open minded might say, that even though it was EVIDENT that it rained, we can’t really KNOW unless we actually SAW it. Something else MIGHT have happened. Hence, being TOO open minded and being CLOSED minded (not knowing unless we see it) come pretty close to the same ends.

When the mind is opened at both ends.

It is not a compliment when it is just another way of saying you are doing a great job of being politically correct.