Can anyone think of good ways to notice when outright deception is being used? How could a rationalist practice her skills at a magic show?

Most "rationalists" are quite smart people, so tricks that are designed by a trickster to fool the masses rarely work on us. For example, I doubt that many on this site would invest heavily in a pyramid scheme or get fooled by a used car salesman. This is because these tricks are targeted at the average idiot.

However, I have recently noticed that there is, for each of us, a stalker who stalks us and at each and every turn attempts to deceive us, and is just as smart as we are. That stalker/trickster is your own cognitive biases, and by far and away inflicts the greatest material losses on you. This is certainly true in my case.

I cannot even remember the last time I was fooled by someone else, but now that I am working on reducing my losses due to self deception, I realize that basically every day I engage in successful self-deception: I get into some emotional state, myopic, irrational algorithms take over, and I make up little excuses to myself for why they reached the right conclusion.

The real enemy is already inside your head.