The other day we covered that you do not need to and likely shouldn't disavow off topic links.
Today, Google's John Mueller is strongly suggesting you do not use the disavow tool to disavow links that "fall low on some arbitrary metric."
One SEO is suggesting to another webmaster to maybe disavow links that have low social media value, such as low Facebook shares or Twitter tweets or Google+ shares. Or even look at the number of promotions, forums discussions and maybe classifieds the links have. If they are low, then disavow them, this webmaster said.
John Mueller said "that's a really bad idea."
That's a really bad idea. Disavowing links just because they fall low on some arbitrary metric doesn't make sense.
Forum discussion at Google Webmaster Help.