The best alternative is to check the size property. If the size is 0 then the document is a delete stub.
Another way to check is the universalid property. This is empty if the document is a delete stub.
How do you code it well you could do:
if doc.isdeleted or doc.size=0 then
'probably deleted
else
'doc is not deleted
end if
Update 13 December 2007
You can use lotusscript isvalid for NotesViewEntry to see if it is deleted or not.