I was reading a magazine and saw what looked like an ad for a miracle cure for memory loss.  

And then I noticed at the very bottom of the ad

OFFER NOT AVAILABLE TO RESIDENTS OF IOWA

So I did some digging and it turns out that scammers avoid Iowa because of their consumer protection laws:

The Consumer Rights Act bill gives Iowa consumers that private right of action pursuant to Iowa’s Consumer Fraud Act, Iowa Code § 714.16, if they suffer a loss of money or property due to deception, misrepresentation or other unfair selling or advertising practice, and allows them to seek damages and attorney fees if they win. (Source)