[MicroBerto]

My thoughts are that the spammers were backlinking their backlinks.

You had blog comments open for a bit, so they got a successful comment link from your site/domain to their crappy handbag site.

THEN, to give their links more "power", they sent low-quality spam links to your domain.

That or negative SEO, as suggested.

Either way, petitioning Google for reconsideration and doing lots of disavow'ing until you're blue in the face could be worth it.