Well, it wasn't exactly advertising, but does it count if I bought something that was totally different after I brought it home?
A while ago, I was at the pet store and holding this pretty little corn snake. She was calm and just slithered through my fingers, occasionally coiling her tail around me for balance.
I adopted her the next day.
Once she got home, she turned into a nasty little thing. She strikes, bites, and does not tolerate anyone picking her up. Her teeth once got stuck in the sleeve of my hoodie when she was trying to bite me. She hides all day and if I move the substrate to get her out, she coils up and if I come near her, she attacks.