How would the average consumer spot a fake mask on Amazon? (jonatron.github.io)

I got some of the Rainbow Symphony ones directly from their site, not Amazon, but the copy on the viewers is strange (it says something about "wearing" but you don't wear a viewer, you hold it, you wear glasses) and they've been sending me weird emails, so I'm a little scared to use them come eclipse day.

I tested it on normal sunlight and I'm not blind, but people say it's different when it's dark out?