Does Gambling Master training actually do anything?

[godamnsteemsux]

Supposedly, Master makes NPCs willing to gamble away all items that they wouldn't normally sell, but since Expert already makes them willing to gamble away equipped items, its advantage over Expert is that they'll gamble away unequipped items.
The only way to gamble for an item is by dragging it onto the dice icon, which exists only in the shop screen. Therefore, only shopkeepers can gamble away their items.
You can't see the unequipped items in the personal inventory of a shopkeeper in the shop interface, therefore you can't gamble for them.
Therefore you can't gamble for the items that Master training is supposed to make available for gambling. Therefore the Master training has no effect. Am I right?