supid mistakes

Q:
If you make a stupid mistake, is it stupid if:
1. you would not have made it, had you all the information and thus would have avoided it?
2a. you had all the informaition, and knew it was not the right thing to do, but did it anyway?
2b. or, there was something "righter" to do that engulfed it?
3. it seemed like a good idea at the time (not meant in a silly "I played billiard naked at a party" kind of way)

Discuss.