[Joe Bork] Mostly, I get angry about bugs that aren’t discovered until after the product has been released, since this means that the test team missed something, and we tend to take things like that rather personally. However, there are a few cases where we (and by “we,” I mean “me and some other people on my team”) find a bug, and perhaps the developer has even produced a fix for the bug, and yet we ship the software without fixing the bug.

Joe describes in depth how seriously we take bugs - it’s well worth the read.