I've started blocking results using ublock last year after it has been mentioned here, and I've got to the point where I have a script I can use to generate the relevant filters for google/bing and a few other search engines.
When I spot any domain which has been squatted by SEO and useless comparison-alike websites I immediately block it. This has brought up the quality of results IMMENSELY.
I'm blocking domains on a _daily_ basis.