Often times when I see a DJ at a Rave (or Rave like event) or at a late night club (Vanguard, Avalon, etc.) it will just feel like one continuous similar song. I know that they want to keep a party going by keeping the vibe but when I'm at Nocturnal and Christopher Lawrence is playing electro and I can't distinguish him from the previous DJ I realize I could be seeing any DJ or listening to a live mix on a CD/DVD with no difference.
It's almost as if they could just hire an actor to stand up there and pretend like they are spinning with pre-recorded tracks playing.
This doesn't happen at say Coachella, Bonnaroo or a venue like the Troubadour or Echoplex just at Raves and late night dance clubs.