Minor quibble but...
The only time you can look into someone else's bag, is that board space where you steal a bean from a person's bag and give them one of yours. They don't have to tell you what they have before you pick them, but once you pick them, then you get to look into their bag and take a bean of your choice.
(I don't have the game in front of me, I can't remember if there is a card which allows you to do the same or not)
Although I guess it still stands that YOU can't show anyone what's in your bag. Just that someone may play a card that allows them to come looking.