What constitutes “bad links”?
A bad link is simply one that violates Google's guidelines.it can lead to Google penalties.
Bad links are those who are not follow the google algo's guidelines, it generate google penalties.
Bad links are those that violates Google webmaster guidelines. They are harmful for your website.
A bad backlink is a link that comes from a not-so trusted website.
The link that violates the google policy called as bad backlink
Links from adult domains can also considered bad links for your website.
Bad links are those couldn't meet google guidelines or violent links.
The spammy links from blogs & Paid links.