My website (Trade Hub has a spam score on Moz of 34%, I do have what seems to be spammy links, especially from a dead domain no longer existing that used to redirect to this one. I haven't disavowed any domains/links yet, because @jocameron said in this post that backlinks aren't counted towards the spam score, only "sites with similar features found to be penalized or banned by Google"
https://moz.com/community/q/topic/61742/how-to-reduce-the-spam-score-of-the-website/61