It's not a mountain out of a molehill. Other than being annoying (and it is. I believe Linux deserves better cleanup of such stuff at its current maturity level), it is plainly bad. It is even a kind of DOS vulnerability: all the X error messages are collected in a file in your home directory, and that file can grow exceedingly large, up to actually eating up your disk free space.
-- X Error: BadDevice, invalid or uninitialized input device https://launchpad.net/bugs/42553 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
