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Hi Mark, Don't fret too much about spammy links. According to Google, they try to limit negative effects of third party sites. Spammy backlinks that bring you down usually come with a "manual action", that is a big penalty sent down from the big man Google himself. These actions are made when it appears these spammy links are deliberate, paid for, or appear to be "black hat SEO". Unless you've experienced one of these penalties, or want to pre-empt one, you don't need to disavow them. If you want to check for manual actions or would still like to disavow these links and keep track of them, use the Google Search Console.