One thing you have to remember is this, as a company you have to start some where and get your product in the customers hand. I can almost guarantee you Barry Meguire did not start out selling his stuff at A.G.,Walmart,Advance,...and everywhere else that automotive items are sold. Sometimes good products are sold by a salesman at a station or a vendor at a car show.You can't always judge a product by where it is sold or the price.
I seem to recall a story about one of the Meguiars actually offering to polish random people's fenders, however that was ages ago. Back when Milk was being delivered. I'm certainly not saying there can't possibly be a good product being sold door to door. I'm just saying the majority of them are overpriced, and many are junk. As mentioned, Kirby is a prime example, they have been selling door to door for ages, preying on the ignorant.