Good questions.
A sales guy aggressively trying to sell is not scamming. That's why in scenario #1 I would not take the wallet or the money. I don't believe salesmen should be insulting or rude when they don't get their way, but at the same time, it's not a terrible offense. It's just annoying to deal with.
However, modifying my cell phone account to charge me more money so they can get a commission is straight up stealing. They're basically stealing from me (hoping I don't catch it) via the cell phone company, who unwittingly gives them a piece of the stolen money. So they deserve more than being fired. They belong in jail.
I wouldn't set out to scam the scammer here, but if the opportunity to take their money landed in my lap, I wouldn't feel bad doing so.