Am looking in to getting a dual action rotary polisher, probably the meguiars one, to try and remove some fine scratches and swirling that have accumulated on my car over the years and are highlighted by the high gloss black paintwork. I've obviously got the odd stone chip on the bonnet where if you look closely the lacquer is cracked, nothing major and very small. But is it safe to use the da polisher over these or should I go round them and avoid these areas? Also on the roof I have a mark where birds mess was left and the previous owner used a touch up pen (!) to try and improve it. Again it's small and not noticeable really but should I avoid this area with the da polisher?