Depends on the site from where it is coming from. Most of the times, it comes from feed scrapers, and I disallow those
but i can not understand why those links not appears in post trackback, if trackback links are enable. and they post as comments.
normally this happens when someone links your article/post and it will appear as a comment on that article
How i can change this option , my trackback links are enabled but trackbacks only appears in comments which looks like spam so i delete them (seems webmaster want to advertise by spamming my blog)
I have my comments set so that I have to approve them so I get these all the time in my approval section. If it looks like spam I just delete it. If not then I decide if it's a blog or site I want to link to from mine and either post it or delete it.