As someone running a federated server (mastodon); you get more problems with local spam than with foreign spam. Most instances will quickly shut down any spam,

As someone running a federated server (mastodon); you get more problems with local spam than with foreign spam. Most instances will quickly shut down any spam, so it doesn't really fill the federated timeline that much. Local accounts are something you as an administrator need to act on, so they are the annoying ones. In my experience, instances that allow spam are rare and the get quickly blacklisted by everyone from showing up in the timelines (there is luckily a neat middleground between blocking the instance entirely and not doing that; allow local users to subscribe to that instance, which is my default action for all instances that aren't hosting illegal material for me).