A few weeks ago we had a very strange problem with a release. We didn't have the time to investigate it, so we added a hack to workaround it and carried on. I've been slowly digging deeper into the issue this week and finally got to the bottom of it. As it turns out the root problem was that our release builds weren't using the same "make" as the non-release builds! This is absolutely unintended, and could've been the source of even more, subtler errors. Eventually, we would've hit a problem that we couldn't have hacked around, and would've had to make scary changes under time pressure to fix it.
This is a great example of why it's important to remove hacks from your code and take the time to understand the errors you hit. You can clean your house all you want but if you don't find out where the mess is coming from you'll never keep up with it.