Filtering for anonymous users on My Credentials page

[jmestep]

I'm using a section of code from the my credentials page in another page and ran across this:
isAnonymous = userName.StartsWith("zz_anonymous_")

Is that obsolete? Is it a bug that needs to be changed?
I had to use the following so the GUID wouldn't show for the user name
bool isAnonymous = ( CommerceBuilder.Utility.AlwaysConvert.ToGuid(user.UserName) != Guid.Empty);