The blocking works well for me. I can see that I have already blocked many of the npubs that respond to you; I only learn about their 'content' because you replied to them. I see your reply, but - unless I do extra clicks - I can't see the things you are responding too (I mostly use Amethyst, but ...

To block someone on nostr you have to limit all your notes to private relays that limit read access to the people you don't want reading your notes. But then you wouldn't be able to scam people...