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I check the "Links to my site" section in Google WMT on a regular basis. In the past couple of months I've been seeing more and more weird links, from pretty spammy domains and even a few from weird Iranian domains.

It's Needless to say but I have never bought a link or been involved in any link schemes or the like. Like probably everyone in the Internet, I'm in a competitive vertical, and my competitors probably aren't so scrupulous.

The question is, do I actively need to disavow suspicious links? Should I contact the domains and ask to remove them? I have usually just ignored these links, and not wasted time in doing anything with them (since weird automated links are always around) but the proliferation in the last couple months has started to worry me.

It seems to me that it won't be really clear if I am the target of a Negative SEO campaign, and I remember the Matt Cutts video- He basically says not to worry about negative SEO, and to use Disavow only if you get a manual action penalty.

This is why I generally ignored these links, and I believe that my link profile is pretty solid. However as you can see in the answers to this question, its still a contended issue.