If you go to the Voom website there is a feedback link, go and leave your opinion there. I did this about a week ago and got a response that it would be passed on. I classified the "Voom Guide Guy" as a pop-up that is more annoying than the internet pop-ups. At least on your computer you can block the pop-ups.
Fortunately I have only seen him a couple times on Auction. I haven't seen him on HD-Cinema 10. I would be really POed if I saw him there. I also haven't spotted him on Monsters, MOOV, HDNews, or Animania either. Perhaps he is Just contained to some channels, or I am just very lucky.