After the Penguin 4.0 update, Google devalues the bad links in place of demoting the websites that they are linked to. John Mueller from Google was questioned on why the Google search console does not have a way of notifying the webmasters about the bad links to their website. John replied that if the links can be recognized, then they can be ignored as well and there is no need for the webmasters to do anything.
Here are the tweets asking about this:
Google takes manual actions for the bad links to a website, and thus, unnatural links can hurt your ranking. The tools that will detect the bad links algorithmically would not affect your website most likely. Instead of that, those links will be ignored, as if those links were not there and that might be as if it affects.
Any manual action shoots a notification, and in such cases, you will be notified about the issue. But automatically or algorithmically, if bad links are detected by Google, they would just be ignored. So, the logic that Google does not need to inform you about the bad links makes complete sense. This is because you anyway do not need to do anything about it.
Forum discussion at Twitter.