Can some backlinks hurt rankings? Example backlinks from FFA, can they hurt you or simple their value is 0 ?
Some people says they can hurt... and this not the end of problems... if your are getting tons of spammy links, your competitors will report you to google/yahoo and you are scrwed up!
It depends on how fast you are getting your backlinks. If you traditionally get one or two a week and then all of a sudden you get 200 in a day, Google could backlist your site.