I had a few situations with the card "Pure Talk," in which it could upgrade basic starting cards like "Fast Talk" to their upgrades with the "Destroy" keyword, but after I played the "Destroy" copy of "Fast Talk" when its upgraded from "Pure Talk," the basic card is still in my deck after the encounter ends (but it stills destroys itself in the battle). I thought the "Fast Talk" is supposed to no longer be in my deck after the encounter if its upgrades to the "Destroy" side through "Pure Talk." Here's a picture of the card in questions that applies that effect.
Do a negotiation with Sal in which you are using "Pure Talk," and when you play it, make sure that you draw a "Fast Talk" that gets upgraded to its "Destroy" copy. Play the Destroy Fast Talk at some point during the battle, then check the deck to see if you have 1 less Fast Talk after the encounter is over.