Aha. I think Atrios may have pinpointed the reason the Bush family is so sensitive about how Dubya got into the Guard. This sensitivity has been incomprehensible to me--don't they realize that pretty much everyone knows Dubya got special treatment? But most people today realize it was a function of the time period and don't hold it against them too much.
According to an 1988 LA Times article posted by Atrios, Bush Sr. did use this exact smear against the Dukakis VP Lloyd Bentsen. Bentsen's son, surprise surprise, served in the same TANG unit as Dubya at the same time. Talk about gall.
But I guess this is why the Bush family so carefully maintains the fiction that Dubya just got lucky one day. They themselves think its shameful.