barbed compliment

a small compliment that is presented at the forefront of a hailstorm of insults

Example of a barbed compliment:
"You're a very smart person, but you're so lazy that you can never get any work done. The only thing you're actually good at is being nice to people, and even that is a lie, because of how selfish and self-centered you are. You're honestly just a burden to everyone who knows you."