Informal, unscientific survey
1 - never ticketed or stopped
2 - don't know anyone who said they were ticketed. My adult kids were once stopped on my dinghy for no registration, just given a warning.
3 - I would avoid a harbor if they are a PITA, but don't mind at all if they enforce the 5 mph limit in our harbor, which they often do, or if they pay attention to BUI or unsafe operation. In fact I prefer that enforcement.