Well, spam accounts are pretty easy to define. They are those accounts that aim to either promote a certain product/service, or drive traffic to another website/social media platform without providing relevant content or value for the users on the receiving end. If an account is constantly repeating posts, messaging users without consent or sending irrelevant and unwanted data then it is bothering others and disrupt their online experience which can be considered 'spamming'.
And kudos to you for being transparent as well as providing means of appeal/feedback to ensure free speech & access at Relayable/nostr!