I use all three techniques. If it needs to be perfect, I spot the negative, then take forever to spot the white blob back to what it's supposed to be. I've a print where it takes 4 hours. If the issue is in a light, fuzzy area (cloud), I bleach then spot. For everything else I leave it be or apply very minor etching with a surgeon scalpel, generally trying to disguise the fault (break the hair line into bits) rather than removing it. Still, etching usually shows in an oblique light, but not behind glass.
I'd love to learn a better way.