I noticed that too. I bought one and used it once only to notice one scratch on my wheels at the end of it. Needless to say it's staying in the garage now and I do them by hand with just a soft kitchen sponge (and change it each time).That meguiars brush scratches your wheels
I have an Autoglym wheel brush and totally agree, it is soft so doesn't scratch your alloys, but firm enough to do what its designed for.Treat yourself to an Autoglym Hi-Tech Wheel Brush. Because you are worth it .