Commercials are only effective when you already like the product, and they're just having a sale on it, amirite?

I disagree. I try a lot of new stuff through commercials. Example:
ShamWow (don't buy it)
Wonder Hanger (don't buy it)
Strap Perfect (couldn't live without it)
SlapChop (love it)
Windshield Wonder (don't buy it)
Magic Bullet (that thing is a beast)