They are unaccustomed to being challenged. So yes, people like us must seem very annoying to them!
Generally speaking I am very respectful in those situations, just because it is easier to get what I want that way, but on this occasion he pushed me over the edge by demonstrating how he knew already root canals come a high probability of being infected, yet failed to tell me this prior to performing the procedure.
In the UK it wasn't so bad, you could give them instructions and they generally did what you wanted to get rid of you.
In Germany they are put on a pedestal and don't like to be challenged or told they are wrong!
I therefore get most treatments l, including dental checkups in eastern Europe and the service is far better. I've even met a few who have done stints in the NHS and returned home!