What a great topic! Here are some statements I have personally experienced that were very frustrating and even triggering:
1. It's been long enough now, have one of mine, I'm sure it won't hurt.
2. If you're going to be this cranky, why don't you just go back to smoking.
3. Looks like you've put on a few pounds since you quit.
4. Cheer up, it's not the end of the world.
5. If you're still using the NRTs, what's the point, you might as well just smoke then. (actual statement by my family doctor 3 months after quitting smoking)
6. Why don't you drop the NRTs, afterall, the withdrawl is only 5 days.
7. I quit cold turkey when I had pneumonia, I don't know why you can't just do the same.
The list is endless. These are the few most extreme ones that came to my mind.