Indeed, I believe this should be mentioned in a much more prominent place. It should be in the text somewhere, not just in the examples. Thinking back, I can't remember how I learned about it...
It does indeed say this, however I printed it out for bedtime reading and the main bit of code I was studying is spread over two pages so I missed it. On later examination after reading the above again, it got found.
"Rule #17 of Travel: Never try and score dope off Hassidic Jews while under the impression that they are Rastafarians."
- Pete McCarthy, McCarthy's Bar