What does "Guest User" look like when I login to it?

Hi vartovsk1988,

If FileVault is disabled on your Mac, Grant's answer is correct.

If FileVault is enabled on your Mac, the real Guest User isn't available. Rather, you'll restart to macOS Recovery (which does have a gray background), and Safari will automatically launch for you. When you quit Safari, you'll leave Recovery Mode and your Mac will restart.

You should get a typical desktop pattern, but nothing on the desktop. Folders Documents, Downloads, Pictures, Movies, and so on should be available in Finder, but they are empty. if you put anything in them they will be discarded when you log out.

All system-wide Applications and Utilities are available.

There is a setting for "simple Finder" but that should show a screen with some Apps on it.

Thats for clarifying that. I did not know about the difference under FileVault.

I stand corrected.