it depends how and what you are searching for, I've seen some "spam" with stackoverflow clonse, but that seems to be gone now mostly. I also think that you are exaggerating a lot, otherwise citation needed.

uBlock plus some filters that remove the ads. Someone also made one that filters out the stackoverflow copy sites.

lol. I noticed it depends on what I search for. I typically search for programming issues. Google tends to have the correct Stack Overflow answer up at the top. But I agree a bunch of ads otherwise.