I wouldnt have a problem with buying one, if the price is low enough to outweigh the drawbacks, and so long as it has been repaired properly (get an inspection done to be sure).
As for what spruce says, while you have a point, the same can be said of any repair, not necessarily a cat d. I could have someone reverse into my car/van in a supermarket car park and crunch the wing, how do i know how well it was rustproofed (if at all) before being fitted?.