From the comments here I'm pretty sure "grumpy" and "bad tempered" are being used to describe far too many things and some of them are pretty bad.

Getting in to a rage and throwing things or just being vitriolic is not grumpy or bad tempered. You can be grumpy with how things are and state your mind firmly and easily be categorized as such. I wouldn't think that's a wrong category either, but it's absolutely different from disagreeing with others and then throwing things.