I like to talk to these people when I meet them. I will ask them something like this.
"That looks great! I need one to provide power for my cabin which is off the grid, so I do not have to handle gasoline for a generator. Does it make 110 volt power or will I have to provide my own inverter?"
"What is the cost per kilowatt to use one of those? .... You mean you don't have that figure? Then how can I compare it with wind, solar or gasoline generators and know which is most cost effective?"
Asking questions that require concrete answers usually shuts down their babblespeak. It also works well for cultists that are trying to recruit you.