This is interesting. As a person who differs somewhat from the norm, OK I'm fat, I find that whenever I get my swimwear on its an occasion for some of my fellow holidaymakers to take a quick snap. (for look at the fat bird photos I can only imagine ) Now this doesn't worry me one jot, I'm comfortable with who I am and what I look like, but it really upsets those people I happen to be with at the time, be they family or other guests, its even nearly come to blows
On the other hand I was on the beach in Spain and wanted some general beach shots till some guy came up to me and asks " are you taking pictures of my birds t*ts?" with so many topless women on the beach, and the fact that I am female I hadn't even noticed I tried to point out that due to the close proximity of people on a Spanish beach in peak season that it was inevitable but he was unimpressed and told me where to go, and not very politely either.
So whatever you do, photography does offend, smile and ask, use a sneaky long lens, each situation has to be decided at the time I think.

Lynn