I worked with a a fair amount when I was teaching advanced motorcycling, mostly to plod who'd failed first time around, but also as part of police/govt road safety schemes.
Like everything there are good and bad.
- generally they have a low opinion of the public, largely because they get exposed to the low life. They do stereotype a lot.
- A few (particularly those trying to get on the motorbike schemes) have judge dread syndrome and think they are on a mission, to fix everyone else's bad driving while ignoring their own inability to ride for toffee.
- They mostly don't have much legal knowledge as the training is very much focused on procedure.
- as with anyone, be polite and friendly and you will get treated better.