"Doctor, I know we're at this cocktail party, but I have this pain in my side..."
"Mrs. Smith, while we're watching our kids play soccer, I know you're a hotshot attorney and I have this issue -- I just want your opinion, though. I can't afford your prices. Heh heh."
"Doctor, can you look at my tooth and see if it's okay? I'm sure no one in line at the supermarket will mind."
"Oh, you're in marketing? Great! I have this product, can you help me launch it? I mean, in your spare time, as a friend and all. I have no budget, but that's why you're here, right?"
"Counselor, your daughter's piano playing was swell. While we're here at the reception, could you talk to me and my wife about our, ah, problems? Just fast, high-level."
"Oh, you're a chef at the best restaurant in town? Awesome! We're throwing a party next week, why don't you come and you can do the cooking and show off. Pay you? Um, no, this is for FRIENDS."
And so it goes.
"Are you pregnant?" "How much money do you make?" "Are you two still intimate?" "WHen are you going to have kids?" "When are you going to have more kids?" "When are you going to move?"
You're complaining about a fact of life -- there are a lot of rude people out there. It's not limited to writers. In fact, we probably deal with it a little less than doctors and lawyers, etc.
Shrug it off. If the boor won't buy your book, just smile and say, "it'll be better when you buy a copy; I'll even sign it for you when you do."