Image courtesy magazineart.org
I had a clear and white pitcher that was badly stained by grape juice. Want to know what got it off? Denture tablets. I filled the pitcher with very warm water, put in about six tablets, and let it do its thing (the box said it's done working when the water turns from blue to clear). There were some stains remaining, so I scrubbed them off—they had been loosened by the cleaner. A quick run through the dishwasher, and it was almost as good as new.
Next I'm trying them out on my thrifted milk glass vases with gunk at the bottom.