OP here. I made a silly function that identifies Googlebot, but has 'plausible deniability' built in: http://www.tomanthony.co.uk/fun/googlebot_puzzle.html htt

OP here. I made a silly function that identifies Googlebot, but has 'plausible deniability' built in: http://www.tomanthony.co.uk/fun/googlebot_puzzle.html http://www.tomanthony.co.uk/fun/googlebot_puzzle.html The idea being you could use a function to always send Googlebot down one execution path and users down another, and make it look like you are doing an AB test on a small set of traffic. You could then do something nefarious, such as add spammy content to the page for Googlebot. However, in reality it is not likely to be a viable tactic for any decent quality site, and unlikely to have much of an impact on lower quality sites that may be willing to risk it. It is an interesting idea though, and we research this sort of thing such that we can better identify such behaviours in competitors of our clients.