The only time I tip the guys at my marina is if they do something for me, like bring a bag of ice. This year, the marina sent a letter to all the tenants saying they were going to add a "christmas bonus" of $25 or so to everybody's bill for the marina staff UNLESS you opted out. With a 1200 slip marina, this could be a pretty hefty bonus.
Everybody I know (including me) told them no way, but I'm sure there were a lot of people who ignored it, didn't get it, or felt intimidated to contribute. It also was unclear who the "marina staff" included, as technically I'm one of them listed as such in the marina newsletter as the editor of same. None of the worker bees who empty trash cans, do* maintenance, etc. are listed there.
I haven't heard yet how much was actually contributed / extorted, and probably never will, but I think it was out of place to automatically add a contribution unless you took action and said no.