On Facebook, I recall seeing an ad for a sticker you can put on your phone which supposedly blocks radiation to protect your brain. That is, in my not so humble opinion, a scam product which preys on and perpetuates a false fear. The first time I saw this ad, I recall commenting that it was a scam and people shouldn't waste their money, and reporting the ad. I saw it again recently on my monthly-or-so visit to FB, and the commenting was turned off, which is how most ads are delivered.

On car forums I used to visit, it wasn't uncommon for people to push scammy products, but there were also respected members identifying them as BS.