Any industry that appeals to vanity (cosmetics, vitamins and "dietary supplements", and penis or breast enlargement come to mind) and is as loosely regulated as here in the US will be fertile ground for over-the-top "marketing" (as in exaggeration and outright fraud) and fly-by-night scammers. It pays to be extremely skeptical ... and remember the rule of thumb used in legitimate science "Extraordinary claims demand extraordinary proof!"
On a related note, when it comes to "dietary supplements" and "herbal remedies", I always look to see if it's on the market in Germany - their regulators require the same kind of proof for claims that the US FDA does for legitimate drugs. Kudos to the Germans!
Another related note about penis pumping: In the US, our FDA approves penis pumps, and cock rings, for treatment of ED - and, in fact, publish guidelines for their use at the FDA website. So, there's no endorsement for being safe and effective for penis enlargement, but at least the technique is recognized as safe.