I’ve been doing this for a while, and it’s a neat trick. I noticed the same uptick in stackoverflow clones recently as some other commenters here have, and quickly blocked them too via this method.

It’s worth pointing out, however, that the blocking happens client-side, and that these spam results often end up taking up multiple results slots. This means that sometimes you will get an empty or close-to-empty Google results page.

Ideally, I’d like to be able to configure Google itself to never return me results from particular domains instead.