this makes me crazy too! my mom's yorkie Livy is 10 lbs...its perfect because she LOVES to be outside (they live in the coutry) and she keeps up with my dad's hunting dogs!
My yorkie is 3ish pounds. I was hoping for around 5 but he has stayed smaller.
I also have gotten the "hey did you know you are walking rat?" How freakin rude!!!
I also get the "oh look a teacup" I have stopped correcting people I just smile. I also make sure if someone is rude and then they want to pet him, I say "oh no he bites"
I say pay no attention to these people, life is too short to listen to stupidity...walk away