Now that would be unrealistic. You can't really guess which distro someone is using just by glancing over their screen for a second. You can tell which DE the

Now that would be unrealistic. You can't really guess which distro someone is using just by glancing over their screen for a second. You can tell which DE they are using but not distro, except in the case of Unity and Pantheon, those are mostly used with their respective distros. People don't usually have output of cat /etc/os-release on the screen easily visible for people passing by to see. There isn't that much visible difference between distros if you aren't working as root.