I don't know if it's as clean as all that...I know that some glues turn brittle and yellow with dry cleaning, and the glue starts to flake off and a lot of stones fall off -- but it's not the case that you'd end up with a nice neat pile of stones that had fallen off the dress.

If the glue is at all water soluble, you can pull the stones off a garment by soaking it for a really long time in a tub of water. I recently de-stoned a dress I couldn't sell just this way. I had glued the stones on with Gem-tac. A few years later I soaked the dress in hot water for a few hours and was able to peel the stones off the dress. It took forever though, and several changes of water.

If you do find out something that really does completely disintegrate as you describe, that would be kind of cool.