At least with RA there's the 60-day money back guarantee and a lifetime warranty on the products. That doesn't guarantee that the gullible won't get taken for a ride. That happens in so many spheres of life. At least though anyone with some healthy scepticism can try with minimal risk.
A bigger problem in my view is a lot of low level stuff such as the cables sold by Argos, the supermarkets and DIY sheds. This dwarfs what the likes of RA are doing simply because of the comparative volumes sold. However, it goes under the RADAR because it's not big ticket prices. Fleecing thousands each week to pay £10 for a 7-Pence cable is easier and bigger business than convincing one person that they need a £90 (!) Kimber coax TV fly lead. I'll bet it's a damned sight more profitable too. There's no lifetime warranty on these things.
I can't say that I know this for certain, but my guess is that the number of £10 TV coax cables going through the retail tills on any one day would knock RA's annual sales in to a cocked hat. The products are crap, which is the really annoying thing.
As someone who installs aerials myself, one of the common weak links in any customer's TV system that's giving problems is usually the no-so-cheap supermarket-bought aerial fly lead. They're inadequately shielded, poorly constructed, and often one of the first things to fail thanks to the use of acidic solder which basically eats its own core to pin connection over time. Of course, very few people ever realise there's a cable fault because the whole thing is shrouded in moulded plastic.
Monster Cables is just overhyped gear sold on the basis of dealer incentives.