I do believe that Vanillas(AKA Thunders) have been proven co-doms.
However that seller always has the 'There is something going on here!' lines in his ads. He had a really nice blushy female up for grabs that 'something is going going on here' for 775 even though she was just a nice normal blusher.
And to me that doesn't look much like the vanillas I've seen other then the widish stripe. No faded head, no 'dots'. I wouldn't pay that price for it.