Successful marketing

I was getting the dishwasher ready to start this morning, and Sarah was watching.  She said, "How can you use Cascade?"  I told her that I had tried switching to the cheap generic alternative, but it didn't get the dishes clean, so I went back to expensive Cascade.  She said, "You should be using Finish.  It doesn't leave the filmy residue that Cascade does."  I stopped in my tracks so I could study her.  I asked her how she could possibly know that, because we've never had Finish.  In fact, I haven't even heard of it.  She said, "I saw a commercial.  I can't believe you're still using Cascade.  You know, millions of people have made the switch from Cascade to Finish, and you should too."