At the moment "no one" is on mastodon. The folk there are the few, and are likely a self-selecting group that are resistant to spam or scams. Therefore you don't see (much) spam or scams there.
Of course should it become popular (side note; it wont) such that my mom and her friends are on it, then the spammers and scammers will come too. And since my mom is in my social graph a lot of that will become visible to me.
Enjoy mastodon now. The quality is high because the group is small and the barrier to entry us high. Hope it never catches on, because all "forums" become crap when the eternal September arrives.
