Bagless

I try to make it a habit to bring my own cloth bags when shopping. However, there are times I forget or I am only purchasing an item or two and don't really need a bag either way. In those instances, I tell the cashier right away that no bag is needed...but some of them are pretty quick on the draw and have one all ready to go by then. I have to say, it really bugs me when I grab my stuff to go and they take the bag they were going to give me and throw it in the trash. Why not just reuse it on the next customer? It kind of makes my intended good deed a bad one and leaves me feeling guilty that I didn't just take the damn bag and recycle it myself...