There's always the implicit thread of strong reprisals (e.g. being blacklisted for life) if you overtly try to trick them rather than just making a mistake.

It would be really easy to just show the reviewers a completely different app from what users see. All you have to do is detect the review process and alter your behavior. This could be something as simple as pinging a server which returns "yes" or "no", and you flip the switch on the server after you pass review.

But nobody does this, because the implied consequences for doing it are not nice.