Its a handy list but you forget to add "Use a test machine that has never been used before."
My original thought still applies - you can test any 2 old/used vacuums together with fresh bags or 2 any old bagless uprights and fresh filters; but it is what inside it FIRST that can easily make the testing void when it comes to pick up.
Both vacuums have to be new, both vacuums have to be unused. I wonder how many videos online indicate true testing like this? More worringly, those who worry about it are going on a "sold as seen" campaign.
