Nonsense, and a typical response from someone who knows nothing about more advanced car care. I guess it sounds like a bad idea to someone who doesn't know what they're talking about, but to those who know better, claybar is indispensable and works wonders.
Wouldnt even use a Claybar. Drawing that across the car with contaminates on it is not a good idea. Use a product like autosmart tar remover. Email the company headquarters and get your franchise person in your area.
True, but it's the grimy stuff that's stuck on top that stops the paintwork from catching the sunlight and looking at it's best. Used as part of a full show prep (as I used to do ;-) ) it does make a difference. I guess the useful-rating of it is determined by your view of your car, for your average 'get in and drive' type it makes little difference. For me the goal was ultimate shine and combined with the right wash/bar/polish routine it gave me a club stand worthy car :-)
My following comment is for the benefit of others, not to put down your above comment.... Claybar doesn't really make a lot of difference to the appearance of your paintwork, it's primary purpose is to remove any rough surface spot contaminates such as tree sap, road tar etc. It doesn't make your car shiney like polish and wax does. The whole point of claybar is that it glides ON TOP of a thin film of water, and removes anything that sticks it's head above the surface of the paint.
Their claybar is awesome, brought up my 12 year old car like new. Heat! :-)