I'm sorry but...

[kacie tri-ing]

It strikes me as a manipulative phrase.
The term "bless his heart" used when insulting someone cracks me up, although it would seem to serve the same purpose as "I'm sorry but". Maybe it's because I can believe that the speaker genuinely feels positively toward the person despite the flaw she is about to point out when she says "Bless his heart", while "I'm sorry but" seems hypocritical. The speaker is clearly not sorry at all.

I soon as I read the title, I thought of "bless his heart."

[kacie tri-ing]

Oh, to add, I am a southerner, and the way "bless his heart" is said in a bad way is....(And yes there is a good way and a bad way to say those same three words).

He's not too bright....."bless his heart" as if that cancels the bad thing you just said.

[Irulan]

"I'm sorry, but I can't find the request you sent for information for your supervisor's mid-year evaluation. Could you resend that request so I know what to give you?"

Seriously, what's wrong with that? "I'm sorry, but..." is a perfectly good phrase if you use it when you really ARE sorry about what you're about to say,

That is true.( but) It's all about the disclaimer that might follow the "...but". This is turning into a huge semantics discussion

I'm sorry I didn't pick up any beer, but you drink too much anyway.
I'm sorry I didn't come to dinner, but your friends are a bunch of jerks.
I'm sorry I cheated on you, but I'm not getting what I need.

etc.

[Aggie_Ama]

I am southern too and we say "bless his heart" as an insult. Like "bless his heart he is nice but not too bright". One day I was having the worst morning: spilled coffee on myself, tripped and bruised my leg, something else. My mom sent me a text "well bless your pea picking heart". I laughed so hard I put it under my mouse pad at work (have one with a clear cover). The bless his heart reminded me of it.