A weekend in Vegas without gambling and drinking is just like being a born-again Christian.
Let's say a Soviet exchange student back in the '70s would go back and tell the KGB about people and places and things that he'd seen and done and been involved with. This is not really espionage; there's no betrayal of trust.
Surgery is a complicated thing to talk about, but I guess it could also be a dangerous thing to play with if you're not very secure about what you're doing.