
"At any time, an investigator at your location may reveal to you the Item assets in their hand." This is not just the first step to use the 2nd paragraph's ability, but a flavorful play with the "Table Talk" guideline stated in the Revised Core Set booklet that the hand (and the deck) is hidden information. And I recommended trying this out to get the most fun out of this character. I opt-in to "Table Talk" for the first time recently and it makes the game really interesting. (e.g. Cannot say "Perception" or an amount of icons you can contribute. You have to believe in friendship and go for it if someone says "I can help!".)
It means player cannot just outright say, "I just draw .45 Automatic, let's group up and you play it for me." while being remote. You may hint that you needs Bob's help to buy an item, before finally revealing it once you grouped up.
Cards on hand are not necessarily telling the story that the investigator suddenly found a gun, it maybe that he brought a gun all along but need "resources" to use it, which is an abstract value, in this case it might take some time putting bullets into it, or finding it from deep in the bag, or gathering courage to use it. But when playing with Bob, the story changed to that when you reveal your .45 Automatic from hand, you are asking Bob to order this specific gun (maybe you forgot bringing it) and then pay for it together. This is a win for flavor for your table.
Bob's resource count is an open information, so you may hint that Bob has enough or not enough resources to pay, without saying "4" cost of .45 Automatic before you group up. (However with more talks/probing, it maybe easy to deduce the cost of the hidden information card.) This affects Bob's decision if Bob also need to use resources for his own and adds to the fun of declining or accepting the group up.
On the other hand, Bob with Shrewd Dealings make this more complex to ask for stuff that might be useful for him from all players. e.g. Even if Bob knows someone put Painkillers in the deck and wants it, since deck is also a hidden information, Bob cannot ask for a specific card. No one can answer that they have Painkillers on hand without breaking the character, either.
Instead, the other players need to give a hint to Bob once they see Shrewd Dealings in play (now an open information), and Bob needs to give a hint that he is in trouble. Even when Bob is not in trouble, Bob don't know what could make him even better with cards of other player's hand. So the table needs to speak up (intentionally vaguely). The secret to success as a salesman is persistence, after all!
The game’s areas of hidden information (the cards in a player’s hand and deck) exist to maintain the feeling that each investigator is a unique individual in the game world, and makes their decisions without complete and perfect knowledge of what everyone else knows or is thinking. A good means of maintaining this illusion is to not name, read off, or allude to individual cards that are hidden information (i.e., in a player’s hand or deck)
For example: Wendy wants her partner, Roland, to take an investigate action, and she desires to communicate that she can help. Instead of saying something like, “Take an investigate action; I can commit Perception” or, “Investigate our location; I can contribute two icons,” Wendy stays in character by saying, “You should investigate. I can help!”