Passive-agressive is a true Minnesota trait, which drives me nuts. Minnesota nice? Um, no. That should be Minnesota passive-agressive.
Passive-agressive language always makes you look innocent on the surface. Additionally, it should leave the other person questioning if you were beiong sincerely nice or a total bitch. Anything less and you're an amateur. Also, just being bitchy is aggressive, not passive or passive agressive.
Like when your friend, who is self-conscious about her weight, has dessert in front of you and your friends at a restaurant. You say, "I wish I were so totally comfortable with eating whatever I want and not caring what others think. Good for you." Complimentary or criticizing?
"I can always pick you out of a crowd. Not many are daring enough to wear the bright colors you do."
"No,it's fine if you pick the movie again. Really." Heavy sigh.
"I see you're still wearing pink. I wish I could be secure enough to not care what's out of fashion."
"You new boyfriends seems...interesting."
The classic is from the South of the USA: "Well, bless your heart." It usually means Fuck you. Saying bless your heart makes you look much better and kinder.