Seems to me that buying reusable PLASTIC bags is kind of defeating the purpose of being green. Plastic -> petroleum. Cotton/Hemp -> renewable agricultural product.
And, as flu said, the only time I wash my bags is if something spills. You can get a small cooler tote for bringing home meat and other things that tend to leak and use the cotton produce bags and grocery bags for dry goods and produce.
And, I don’t consider washing a cotton bag occasionally anywhere near as energy wasteful as single use plastic bags. I have a friend with kids that does at least a dozen loads of wash a week. Throwing a couple of extra bags in with his wash occasionally isn’t going to throw the earth of it’s axis.