Chris Bacon wrote
Ah. I'd imagined that the dust container would be to some
extent conductive. Silly me.

No - if James Dyson really was half as good an engineer as he's cracked up
to be then he would have thought of this and it would have been! As it is,
even if you don't get a shock when you empty the dust container, dust is
transferred all over the outside by static repulsion, which is not a good
design feature for a vacuum cleaner!

David