Micrometer style torque wrenches require regular calibration. The only safe assumption that you can make about a used wrench is that it needs to be checked/calibrated. In many cases, the cost of a used wrench plus the cost of calibration exceeds the price of a new tool.

Cosmetic appearance is not a reliable indicator of accuracy. Practically speaking, however, a torque wrench that gets used as a hammer and pry bar probably doesn't spend much time at the calibration lab.