From Ask Figaro:
Some people explicitly try to deny their intention before carrying it out, like “Not to hurt your feeling, but you suck!” What’s the best way to respond to this “Not to…but” phraseology?
Dear Pronged One,
“Uh, how do I say this without being offensive?” mused Moe, the bartender in the Simpsons. “Marge, there ain’t enough booze in this place to make you look good.” The figure is an apophasis, the deny-it-then-say-it figure. One response Figaro favors whenever there’s an audience of onlookers is quiet irony: “I see that your sensitivity matches your intelligence.”