There’s another wave of discourse about The Bad Space on the microblogging side of the fediverse, so here’s my article from a couple of months ago.
If you’re familiar with Fediseer, there’s some discussion of similarities and differences in Compare and contrast: Fediseer, FIRES, and The Bad Space
Your block settings are stored in your account settings, on the server side, unless you use an app that chooses to store that stuff locally (i.e. on Lemmy where many servers haven’t upgraded to a version that does per-user instance blocking).
Any ActivityPub server can choose what servers to federate with and what servers’ content to show. If your current server isn’t moderated to your liking, you can switch to a server that’s more in line with what you expect.
If there are no servers that have the right moderation properties, you’ll have to find like-minded people and set up your own server, where you can block entire servers for you and your friends rather than relying on an admin to do that job for you.
You can block 99% of cartoon penises by disabling NSFW. On Mastodon and similar apps, many people are using content warnings with additional context, but this is not built into Lemmy unfortunately.
As for spammers, that’s just basic moderation, it happens on every platform. The difference between Facebook and the Fediverse is that the Fediverse doesn’t have many dedicated full time moderators, and no fancy spam detection algorithms to automatically hide reported posts. There are scripts to help admins fight spam, but they’re not 100% effective.