I'm really just putting this out there in case anyone else runs into the problem I did.
Basically, installing and running OpenFire on OS X, and then deleting the app, but having it turn out that some installed binaries keep running in the background and writing to error logs that quickly expand to fill many Gb's of space on one's hard drive. Furthermore, the used-up space is hard to locate because it's in /usr/local/
Here's the solution I was able to use:
Run this in Terminal to see a list of everything touched by the installer