Two kinds of published review count: user reviews on SkinRecs and first-hand comments quoted from around the web, each linked to its source. Each one is read as positive, mixed or negative. A user review's star rating decides it (4–5 positive, 3 mixed, 1–2 negative); quoted comments are judged when they are moderated, and ones nobody has judged yet don't count. Only reviews from the last 5 years count, and a quoted comment is dated by when it was written, not when we quoted it.
The order rewards products that are both well liked and widely discussed: we count how many more positive reviews a product has than an average product with the same number of reviews would have. A product with 33 positive reviews out of 43 therefore ranks above one with 15 out of 17, which is why the order doesn't always follow the share of positive reviews.
A product needs at least 8 reviews, at least 60% of them positive (mixed counting as half), to be listed, and this list only includes products with a treatment type. We never pad a list: only 9 products qualify right now, so that's how many you see.
The list re-ranks itself as new reviews are published. There are no sponsored placements or paid rankings. The Amazon links are affiliate links and never change the order.