I know that Rick Steves is popular and all, but I live in Europe and these things sound kind of far-fetched. If someone came up to me in Munich, for example, and tried to be my friend, I would think that they are clearly not normal. There's a scam that happens to people with German license plates when they drive through the Czech Republic. Czechs will pull them over, steal from them, and run away. At least I think that's what the scam is. A street thief will just steal from you and run away. All of this talk about being clever and all is just talk, I think.
Look, if people are going to scam you, there's a good chance that even the savviest person will fall for something that is clever and well-executed. Nobody can hope to be completely immune to the things that will be pulled on them. That's just wishful thinking.