What is a toxic link? Are toxic links the same thing as spammy links? Can too many of these hurt your site's ability to rank? If you are uncertain as to whether you would benefit from filing a disavow, this article should answer your questions.
What is a toxic link?
A "toxic" link is generally considered to be a link that has the potential to harm your website's ability to rank. However, not all SEOs are aligned on how to define toxic links and whether their presence actually could hurt your ability to rank.
Some will say that any link that would be considered an unnatural link as per Google's documentation on link schemes should be considered "toxic" and could hurt your site. Others use the phrase to describe the type of spammy link that Google says their algorithms ignore. It is important to note that Google itself does not actually have a notion of "toxic links".
So why do SEOs use the phrase "toxic links"?
Several well-known SEO tools aim to find and help you disavow unnatural links. Several of them list links that they have programmatically determined to be potentially harmful in Google's algorithms. The idea is that you can use their tools to identify these "toxic links" that could potentially hurt your site, and then disavow them.
I believe these tools are attempting to find all unnatural links pointing to your site. But in my experience, the majority of links that are returned by these tools are ones that I would consider spammy or "cruft". Most of these really should be ignored by Google's algorithms. I find that the truly toxic links...the ones that could have the potential to harm your site algorithmically (although you'd have to really overdo it, as I'll describe below), are rarely returned by an SEO tool.