Obviously Which? is a trusted brand and would never want to publish anything that would tarnish its reputation as a trusted public champion, but we will be monitoring any results published.
I can't go into details here, but quite a few years ago I was working for a company on a joint project with the commercial publishers of Which? to develop a product offering a much better deal in a particular market sector, to be launched under their branding.
All was going well until they suddenly stopped responding to emails. We couldn't make it out. Then we discovered that Which? had decided to go with a competitor, offering a much less good product (lower quality, higher price). Oh, yes and a better margin for them.
Of course they plugged their inferior product as the best deal, but I think customers saw through it and they only did it for a while.
I have never trusted them about anything ever since - and that was admittedly a LONG time ago.