Deception in poker: Denying your opponents useful information about your holding.

Notably:
The basic deception play in poker is the bluff, and it turns out that (game theoretical) correct play dictates that bluffs get folded to by stronger hands fairily frequently.

Moreover, sophisticated bluffing -- and, for that matter any correctly applied deceptive tactic -- will be neutral or +EV.

It's also not at all the case that deceptive play is necessarily random. For example, it's possible (and even concievably sensible) for someone to consistently play 2c 3h 4h 5h 7h the same as a royal flush in straight 5-card poker.