Almost impossible to clean a metal straw. I would never use one. Actually, never been offered one.
Putting them in the dishwasher is almost impossible for you? I have them, they are made of stainless steel, and when they come out of the dishwasher, they are probably more sterile than a brand-new Chinese-import plastic straw.
You've obviously never heard of Hoppes #9 and a bronze bore brush.