Yes, spammy links in blog comments and forums posts, may suggest a low site quality indicator (no moderation). Such links interfere with Google’s link graph, and having too many spam outbound links can negatively affect your rankings.

Here is what Google says about user generated spam (which most of the times includes links)

“Comments and forum threads can be a really good source of information and an efficient way of engaging a site’s users in discussions. This valuable content should not be buried by auto-generated keywords and links placed there by spammers” source