In Polnad you pay for what you order, and you give the tip if you want.
Poles never tip. It's rude to tip. ;)
I can remember when I went to Rhodes I hired a moped. Went into the rental place saying "kalispera" good afternoon in Greek. Told them I'd spent some time in Thessaloniki a few years ago. Got me a moped for something like 3000 drax/day.
Went back the the accomodation and told my neighbour about this great moped hire place. He was your typical Brit - not a word of Greek. He was charged a lot more. Something like 4500 drax/day.
This is perfectly normal. What's the problem. If they think you're a foreigner and not savvy they'll take you. You just have to appear more savvy. It ain't rocket science. ;)