A marketer could technically know, if they have their tracking on Ticketmasters sales page...
IME though and assuming ticket master allowed it, it would only be that agency who would have access to the data, it certainly would not be accessible to any old punter with access to Google Adwords!
This a guess or insider info? Been waiting to see where they'll end up playing when they return and would be very keen for a day at APE.
Vampire Weekend I think are out as a UK festival exclusive for Victorious.