There are some sites that are so useless and they have never ever helped me once, yet somehow they are always in the top 10 results
1. w3schools
2. pinterest
3. microsoft answers and all microsoft websites actually (it always looks like the person asking the question is asking exactly what i want, but unlike stackexchange, there are seldom any useful answers)
4. all the code clones for SO
5. all alternative to / review sites like capterra, g2, alternativeto, etc. They might have some good suggestions but they always hide the link to the software/site and instead link it to their spammy page. So you have to select part of the link and then re-search it on Google. Doing this for OSS projects can sometimes lead to a whole new rabbit hole.
6. The best of lists. Google for the love of god, please ban them.. they are always always SEO spam and product placements. Often the blog post itself says "to put your product on this list pay us a $1000 and we will include them in our list."
7. Quora and similar answer sites.. okay it's a mixed bag but you have to be very careful on these sites as most often the answers are just spam. I never read any answer with a link in it. But I think it's more Quora's problem than google. But if google is strict with them they may do a better job at moderating I guess. Also now quora hides answers and asks for a payment. Did they learn nothing from experts-exchange!
https://github.com/iorate/ublacklist
https://blog.probabletrain.com/hide-w3schools-from-search-re...
With some lists to block the SO and Github clones:
https://github.com/arosh/ublacklist-stackoverflow-translatio...