Yeah that's one of the reasons why I don't really like using powder. Had a similar experience before where after using Capture, I had to sweep off the vacuum after using it not to mention some powder had leaked out of the bag. I'd have no problem using the DUO for hot water extraction like what this professional does.
The Riccar is the only one so far that made a mess with the powder. The Riccar is also the only vacuum I have that spits everything that isn’t dust or hair. I’ve never noticed leak in any of my machines, the X4 sometimes when you open the bag door. I always have to dust the top of the Duo machine off. I also don’t really notice the Duo power getting anywhere it shouldn’t, unless I get a bit rough when shaking the powder. I usually try and sprinkle the powder close to the carpet.The caliche desert dust where I live is about as bad as that powder. I always have to put the dusting brush on the hose and vacuum the nozzle top and bottom before I park it to remove the dust that clings to everything. Then if it's a canister I have to vacuum off many of my canister vacs because they always have a bunch of pet hair clinging to the bottom from static electricity build up.