I use it the "good" way, too. It upsets me when this topic comes up, because it is almost always my first response to someone who is hurting and I mean it sincerely.
Now, because of people saying it's insulting, there will be some who are offended when I write it and will think I'm making fun of them.
Do I have to write a disclaimer, every time, at the bottom of my "bless your heart" posts? I think the mean people should write */sarc* after *theirs.*
Bless your heart!
"Bless your hear" generally is catty when it's used after a back-handed compliment.