I'm not sure how this would be implemented. Where would the blacklist be held and how would it influence the search results? I know that they already do a lot of search customization but most of it is just aggregate statistical computations. It's not that they return results specifically tailored to you but more like results tailored to a very fuzzy average version of you. A blacklist seems way too specific to each u…
Presumably it would do the same exact thing as '-site:foobar.com'.