Two of the vases that came (she did offer to just throw them away but I said, "oh just leave them, I'll see if I can clean them") were pretty yucky looking. They had been sitting under a sink (I think it must have been drippy) for years and had a major calcium (I think) build-up as well as who knows what else.
I decided to try soaking them in some Vinegar water (about a cup of white vinegar in a sink half full) overnight and guess what? By morning everything scrubbed off very, very easily!