I ran across an excellent example of BS just a day or two ago. It was an electronic pest-repeller. Plug it in, it drives away pests, supposedly. The funny part was, it was sold as the "Ultrasonic Pest Repeller". Then in the sales blurb, it quite clearly said that it produced sound of a frequency too LOW to hear, and that dogs and other pets couldn't hear it. I thought I'd misread soemthing, had to go back and double check the name and description. And no, it was not a huge subwoofer type thing, just a little gadget that plugged into an outlet.
And, long long ago, I remember seeing them sell plastic owls. In the gardening magazines, plastic owls would scare off crows and other birds. In the hunting magazine, "Crows hate owls and will gather to attack". So the same plastic owl either attracted crows or drove them away, depending on what you were wanting it to do. I'm not sure how it knew the difference though.
And that reminds me of another story, where the person described how a thermos bottle kept hot liquids hot and cold liquids cold, whereupon the other person asked, "But how does it know?"