I often wonder if banning (or very strongly penalizing) websites with affiliate links would largely get rid of spam results. Sure, some very useful websites have affiliate links, but perhaps it would be worth it to at least let users hide them?
A solution could be more than one algorithm being used to rank results, i.e. other engines, other rules. They'll likely use many of the signals available to them that Google uses for quality and relevance, but highly unlikely a genuine alternative search would rank them exactly the same- and much more unlikely an SEO could rank well in multiple engines.
The aff links aren't the problem, it's the proliferation of pages that are created solely to rank and get the links clicked on. Sometimes the content is useful, sometimes it's padded nonsense.
You run this bloated mass as a co-engine to your search. If you stumble upon any of the digested sites or articles you just have the site-eater blob regurgitate a html re-creation locally. They get no traffic, you get whatever they wrote purged of all links and with optional formatting to remove the fluff BS copywrite that many of these sites pad the tiny core of usefulness with.