So you might have (made up example) an Electrolux vacuum getting a score of 73, but a Dyson gets a score of 74 and wins their "recommended buy" then you see the Dyson is, like, twice the price.
I can see they might do the review price-blind, but it does make one suspicious that they get some sort of financial benefit from having top picks be vastly more expensive products.
Useful reviews though.
It's one thing for some shady website with little to no reputation to lie about these things, but Which is an old company whose model is entirely based on trust.
In your example, you can see very plainly that the Electrolux is a much better buy. If they'd included cost in the rating, you'd probably be left wondering whether the Dyson was worth the extra.