I tend to prefer that old preference files be left around - they don't cause me any harm (not even a feeling of clutter, since it's not like I'm poking around ~/Library/Preferences all the time) and if I ever reinstall the app, I'm right back where I was. I can understand that it does bother some folks, though.

I can indeed understand your sentiment also. Hence my description of my behavior bordering on something close to OCD. I think I get that "feeling of clutter" a lot more easily than many people :P

For whatever reason though, I guess I don't really reinstall apps very often. Once I decide to remove something, it's almost always after pondering the issue for a little while and making a decision that I very rarely go back on. The only time I can remember reinstalling something on my Mac was Filezilla. I got myself a new FTP client, removed Filezilla as I didn't think I'd be using it anymore and then found out that my new FTP client had a bug that prevented proper connectivity via FTPS. So I went back to Filezilla and as luck would have it, Filezilla's preferences are stored in ~/.filezilla and they were all still there (because I didn't know about this directory). That was a small time saver.

I suspect a great deal of my attitude towards being (likely overly) careful about what I install/uninstall and what's left behind afterwards comes from my many years as a Windows user. I remember it even took me a while to figure out that you can usually just drag stuff to the Applications folder to install on a Mac, I kept thinking to myself "I'm missing something, it can't be this simple..."