After around a dozen failed attempts I finally found a great solution 9 months ago. Of course two days back I accidentally left it in a hotel room. Trying to buy a new one by clicking the link from my purchase history brings me to a listing with completely different pictures that look nothing like my beloved mask, now includes bluetooth music playback functionality, and of course costs about 3 times more. Pretty sure I won't get the same product if I bought it again.
So really I'm wondering if my previous 5 star review counts as a "fake review" based on this study's metrics and if not what percentage on top of that 30% is earnest reviews that are for completely different products.