I have purchased several items "as seen on TV" but *never* *EVER* by calling a number or ordering from the net. I always waited until the item made it to regular shops. Very few items are genuinely good enough to make it to a regular shop. Most of those wonder products depend on people ordering them without seeing them in person. There is special "as seen on TV" shop in town and the vast majority of products there are ... not the quality I would be willing to use, even for free.
However, I do love watching those shows pushing questionable products.
Over they years I have purchased following wonder products:
- blue magic mop
- "Swedish" microfiber cleaning cloth, such as
http://www.microfibersunlimited.com/products.htm . But much cheaper generic version. Fantastic for cleaning an e-ink screen and many, many other things.
- hot air oven (wouldn't buy it again), similar to this one
https://www.asseenontv.com/detail.ph...09bbf0faa22348
I would never buy a knife from a TV commercial. I bought a simple chef knife in store where big caterers purchase professional equipment. Ugly, utilitarian, durable, made from a good quality steel. I have very well equipped workshop with several electrical grinders - including a wet stone one, so I can sharpen anything I need.