So sure, bugs happen, regardless of how good you are.

But there really are some people who constantly make mistakes, and those that rarely do.

There are people on my team where, when there is a bug, I just start looking at diffs of what they have committed because more likely than not, they caused the problem.

I think it's important to reinforce an attitude of trying to become better and people who give a shit when they make mistakes tend to also be the ones who make less of them.