I may not necessarily have the same criteria for good software as dragonchild, but no, it shouldn't depend on the person who comes in. I think that's (part of) dragonchild's point.

Anyone should be able to come in, make a change to some small part of the program, and be reasonably certain that everything else continues to work as before, with this modification. I do think this ideal is a wee bit lofty for any set of requirements that approach moderate complexity, but I think I see where he's coming from.