Using a backlink checker I found hundreds of old spammy links that actually aren't there anymore.There are probably thousands more that have long since been removed.Is there any reason I would need to retroactively disavow a link even if the link doesn't exist anymore?   And do historic links still confer link juice?
SEO: Is it necessary to disavow historic / deleted links?
seo;disavow links
If Google does not know about it, do not worry.Backlink sites are extremely slow and inaccurate. It is not uncommon that links that have disappeared remain on these sites for quite a long time. The most accurate view of what links exist for your site comes from Google itself- especially if you are in trouble.Do not use these garbage sites. Ignore them. Use the standards that matter; Google and Bing.There is no need to disavow links that Google does not know about and are deleted just because you see them on a junk site.