Four of the top ten sold nothing at all.

Because the subcategory is tiny. Amazon.co.uk lists 12 products under Percolators in total, and COLETTI has five listings inside it — the plain Bozeman, the black Bozeman in two sizes, a second listing of the plain pot and a pack of spare glass tops. In a category this small a single active seller can fill most of the page.

Ranks 5, 7 and 8 are replacement glass tops and a basket lid, not coffee pots. Amazon files them in this subcategory, and they clear the same review and rating filter as everything else, so they appear. We flag them rather than quietly dropping them, because it tells you something real: in a category of 12 products, a quarter of what sells is repairs.

Not necessarily, but read them carefully. Ranks 7 to 10 recorded no units during the observed period, so their star ratings come from historic buyers rather than current ones. A listing with hundreds of reviews, a bestseller rank in the millions and no throughput is usually one that has quietly gone out of stock or out of favour — the Stansport entry at rank 10 does not even state a capacity.

The products are ordered by estimated monthly revenue per ASIN, not by star rating and not by bestseller rank. Only products with at least 200 reviews and an average of 4.3 stars were included. The whole top ten turns over roughly £2,250 a month between them, so small differences in units move the order a long way here.