My boss is a jackass.

I've had the odd incompetent over the years but always tried to give them a wide birth whenever possible and especially in physical confrontation situations.

Everyone has them, just like every employer deals with incompetent employees.
The people I have most problems with are engineers and safety officers who don't know their job yet still have to be dealt with....I find that asking them a question is a very good way of getting rid of them.