Re: Smart is fun - I'd love to try it in real life!
I can also see arguments for and against vacuuming, but there is supposed to be a way to "reincarnate" a dusted vampire by adding blood, so a player vacuumed up vampire dust in a game I was in. She wanted to ensure that he couldn't be revived without her knowing about it.
(OTOH, a demon character who travelled as smoke so he would have some idea of where he was going hated having to pass through a fan...)
It really needs something that would stop the atoms of dust reforming into the vampire.
Ahhh! If you use a vacuum cleaner with a cloth bag, not paper, you might get rid of the vampire permanently by thoroughly soaking the bag in holy water - it can then be left to dry almost completely before sucking up the vampire.
Any vampire dust in contact with the bag (and certainly any dust that is forced through the mesh of the cloth) will be damp with holy water and should be lethal to the vampire when it tries to reform. It can be expected to burn so the vacuum cleaner may not be much good afterward.
It has just occured to me that one could use a vampire as a bomb, given the right trap...