I haven't had any flat out bad deals yet - I'm only buy when I'm confident I can resell the gear and break even worst case - but I have made some bad guesses about what I'd like. As for deals that didn't work out in my favor, the best I can do:
- 70$ for a Moskva-5. Looked good but has a slightly bent strut and a rear element with... what looks like either uneven glass or a glob of coating on the inside of the rear element. Between the issues, the images are way too soft and uneven to be useful.
- A $35 FED 2 in need of repair that turned out to need parts, not just repair. And that had a recessed accessory shoe incompatible with the finders I have. I still have the camera in parts as I haven't had the will to put back together a non-functioning camera.
- A Minolta 7sII for $55 that had dead electronics and a touch of fungus in the rear element. I'm holding on to it for now, hoping to I can get it repaired myself. Unfortunately I'm having a heck of a time getting into the guts of the camera.
- A bunch of rangefinders I picked up with the intent of repairing and selling. I already broke even and enjoy the education and work but I know its taking away from shooting time. I'm probably making $3 an hour doing it and anything I make is going towards professional repair on cameras from that batch I'm keeping. Opps.
All things considered, I've done okay as I've been focusing on interesting items I can buy cheaply. I don't have the fortitude to spend more than $300 or so at a time.