Dear Evan,
You could get a Google manual-penalty, or simply be affected by an algorithm penalty (Penguin), so the best practice is:
1. Contact the webmaster of these sites and ask for link removal.
2. The remaining links should be included on the DISAVOW file at domain level.
You should be use to construct your link profile several sources, such as Google WMT, Bing WMT, Yandex WMT and of cours several tools such as ahref, SeoMoz, LinkMajestic and LinkDetrox, and other tools, each bad link you detect and get remove from there is a goal and prevent future penalties or gradual downgrades of your rank.
Good luck