One-Liner: Find a Renamed and Relocated AD Guest Account WITHOUT using the Well-Known SID
So... someone decided to rename and move the domain's Guest account.
You could find searching via the well-know SID...
Description: A user account for people who do not have individual accounts. This user account does not require a password. By default, the Guest account is disabled.
Or... you could try this little trick...
Get-ADUser -Filter "primaryGroupID -ne 513“