I see this type of thread soooo often, i do wonder where everyone lives. I am in MA/NH and noone here would EVER pick up my dogs! haha Ive had people come over and ask questions and pet them and Ive done it to other people's dogs. My boys BEG to be pet, no person could resist when they are stumbling all over each other to get to the person who is looking at them! haha
The best way to avoid, is not take them out. Otherwise you'll just have to say something like "You can pet, but please don't pick her up." or "She bites" that should keep people away! LOL Or you could carry her in a carrier! Some people have no manners. Sorry its uncomfortable for you!
I know when I take my boys out they are going to get attention, its inevitable. I leave them home when I don't want the attention, and I take them when I don't mind it.