I am currently self-hosting a meta search engine instance (searxng), which allows me combine searches from different engines (e.g. Google, Bing, Yahoo, etc), but also to filter out websites that I don't want to show up.

The only website to make my blacklist so far is slant.co (useless SEO-riddled site that always comes up when I search for software comparisons). I also automatically redirect all reddit.com links to old.reddit.com.

I'm looking to expand this list. So, which websites do you blacklist? Either using software, or just mentally.