This might be useful to blacklist some of the shopping results when you want facts and not shopping results. Sometimes I google "how does X work" type questions, and I get pages of links of things I should buy. The top stuff are obvious ads, but the non-ad results are basically shopping sites, too. That's mean of Google. They're our main source of information ("How does X work") and instead they want to redirect you to shopping because .. they can.

I notice -shopping helps... magically. But not enough.

Maybe the blacklist is the right idea. Can there be a magic incantation to exclude or include groups of blacklisted sites on a whim?