Pat - I have one of those little blocks, but mine has teeth like a Bastard file. I don't like it either. It leaves scratches that are as difficult to deal with as the run I'm trying to remove! I've seen other painters shave a run with a razor blade, but when I try that it always digs in and leaves a divot in the paint that has to be sanded and repainted. I guess I don't have "the touch" needed to make it work. I've never seen what you call the "snot block". Do you know where it came from? I'd like to try one.

You're right about old-time enamel. I remember old Dupont Dulux; no hardener, no cross-linker, just paint and reducer. If you could spray that stuff and get a good gloss with no runs, you were a MASTER PAINTER! Life in the paint booth was suddenly much easier when acrylic enamel hit the market...