Had an annoying brake squeal for a few weeks now, finally got time to look at it. This may or may not have been pushed up my priority list by the acute smell of brake as I got out the car at work.

Hot discs!

Strip down and as I guessed, the pads had corroded tight into the slides where the paint had bubbled up. Why didn't I file them down and copper slip them when I installed them?

Moral of the story. Don't rely on paint to do a anti-seize compounds job!