Well, you can be surprised. It's surprisingly common, in my experience, to believe people who pretend they are on your side. One interesting and typical case that is documented through countless online videos is police interrogations, where the interrogator is usually an expert in making it seem he (or she) is on your side, despite how obvious it should be that they're not. "Can I get you a meal?", friendly tone, various manipulations and before you know it you've said things that can and will be used against you whether you are guilty or not.

And you don't get the meal, either.

> We can also mention the case of psychiatrists running the "Presence francaise" groups who, appointed to examine the prisoner, started off boasting they were great friends with the defense lawyer and claiming both of them (the lawyer and the psychiatrist) would get the prisoner out. All the prisoners examined by this method were guillotined. These psychiatrists boasted in front of us of this neat method of overcoming "resistance."

- The Wretched of the Earth, Frantz Fanon

I read some of the pages before and after that footnote. Highly disturbing, to say the least.