Living up here in the Smog of the North we need them.
Having worked on Chemical sites for 10 years you'd be suprised whats landing all over your pride and joy.
All of the sh#te that we put up in the air where I work (a bit of Sulphuric acid vapour Sir?), that floats about a bit, then lands on our cars, is taken off with this thing.
Do yourself a favour and buy one, "Quick detailing claybar system".
Just as a test, clean your car then polish it. Then rub your clean hands over the paintwork, does it feel bitty? Mine did, totally sh#tted right up. This thing takes it all off.