Meta keywords no longer work

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Nicos Christou: Hi, quick question. I know that meta keywords no longer work for Google and having them provides no SEO benefit. However does it actually count towards spam if you have them in which case you get less rankings because you still have them at play?
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  Jon Tromans: They probably only count as spam if you put spam in them :) Otherwise they are probably ignored......
• 
  Federico Sasso: As far as I know, Google never mentioned it as a spam signal, they just kept saying they never bothered for it.
  The idea of the "spam signal" comes from the interpretation of an old statement by Bing's Duane Forrester. He once declared something like "if we find too much keyword stuffing there, we might wonder how much spam is in other parts of the site, and might want to check a little more".
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  Dave Elliott: i remember there being something about should your site ever be flagged for a manual review then one of the things they check is meta-keywords which may count against you, as you clearly haven't been paying attention to the industry for the last 5+ years...... but it won't count against you in an algorithmic sense.
  
  meta-keywords do make competitor keyword research a lot easier though, so i'd always advise taking them out if you have the time.
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  K. S. Bisht: you have got the answer :)