This is often just the directory in 'Program Files' and 'Program Files (x86)' and possibly a few files or directories under it that for some reason the uninstaller was not expecting. It might also be worth looking in ProgramData and it is possible that the uninstaller left some Registry data. In terms of impact it is not likely to be significant.

Thanks for the reply, that's kinda what I thought. I can see the advantages keeping some things around, but man I like a complete remove all option and not something vague.