I use bottom of the barrel, garbage left-overs to paint groundwork, trees, buildings and such. By the time I'm done with the washing, dry-brushing, colored pencils, pastels, ect., it doesn't really matter what I threw down as a base coat. But for my vehicles, they only get the top-drawer stuff, usually a new bottle, especially if it has been open for a while. I have paints of all types, from the cheapest Mall-Wart junk to Winsor & Newton oils. I use them all.