I don't automatically let just anyone pet my dogs, even if they have the courtesy to ask first. It depends on how the people are acting. My problem with Hazel is keeping her from laying down and rolling over for a belly rub. LOL She goes to work most days with DH, and she lays by the doors of the shop so that anyone who comes in has the opportunity to give her belly rubs. Because most people do, and lots of folks come in strictly to see her, I guess she assumes that no one can resist her and will pet her. Because she is big, and people think she's black (she's actually grey but you can't tell unless she is next to a black dog) some people assume that she's mean and will give her a wide berth - which breaks her heart. If she sees people ahead of us, like if they are standing on the sidewalk having a conversation or something, she'll start to pull me to get to them quicker. They see her pulling me towards them and I can tell by their body language that they think she's aggressive. I'll start calling out 'don't worry, she's friendly and just excited at the prospect of getting petted'.
People don't try to pet Malone nearly as often, and he'll shy away from anyone that approaches him too quickly. Maybe he just doesn't have the cute appeal that Hazel does. When people do ask to pet him, I always ask them to approach slowly and pet him under the chin - he really doesn't like strangers trying to pet the top of his head.
The biggest problem I have is with my son's SharPei, Lexi. When we are at our lake camp, we often have people she has never met before in our camp and people assume that because she is smaller, she doesn't present a threat to them - but she can be really iffy about strangers petting her. She especially doesn't like it if someone tries to get her to roll over for a belly rub - there's not many people she will expose her belly to, even if she likes them. She also has entropion, and has had 2 surgeries already to try to correct that. Her eyes are very small, and I think she has trouble with periphial vision so she can be easily startled. I always tell people that if she wants them to pet her, she'll approach them and otherwise to leave her alone.
Livin in a Newfie Drool Zone