They need to be non traceable. If I'm doing something underhanded with pricing information I want to detect Google and other such bots and give them different information.
They're saying if they were to lie to their customers, they'd want to make sure they're deceiving Google. In that case, having an easy way to detect that it's Google would make that trivial.
Is it wise to intentionally refrain from offering the same price to a human you'd offer to the Google-bot? Possibly. Depends on your goals.