John, I bought an older canon 20-35 L from KEH with a bargain rating and i was very pleased with the results. There will be dings and scuffs on the metal but generally you are not going to have anything that would affect image quality or require work.
KEH had a Tokina 28-70 F2.8 wide andle lens (Canon EOS) for $159 in condition BGN. That price made it very attractive, if it photo results were perfect I imagine you could live with some scratches on the metal casing. It is gone now, so someone decided it was worth it.