Variable on checkout confirmation page to determine if user is logged in vs guest checkout?

6 0 1

While you can use the customer object to determine if a user is logged in or not anywhere on the site, this seems to always return true on the checkout confirmation page when this is used inside Admin > Checkuot > Order Processing > Additional Scripts (even when purchasing through guest checkout when user is not logged in).  

{% if customer %}


Is there a variable that can be used in this area ( checkout > additional scripts :: where conversion scripts and tags are placed) that will indicate whether a customer is logged in or checking out with guest checkout?

Thanks in advance =)