Dash seems limited by being tied to one item. I don't get the appeal of Dash either because items I know I need a reoccurring supply of, I get a subscription to.

The Dash is a microsphone/scanner wand thingy, distinct from the Dash Buttons

I think the implication is "wet/soapy hands"

Think about what you're doing, and what condition your hands are in, the moment you use the last of the dish soap.