Is it worth going back and retrospectively adding meta tags?

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

• 
  James Hancocks: Greetings one and all.
  
  I have a dumb question that I hope you can answer.
  
  Imagine a blog that has had over 325 posts since 2009 but no meta keywords or meta description added in that time- how counterproductive will that have been to SEO/ page rankings?
  Is it worth going back and retrospectively adding them in?
  
  Thanks in advance for your advice.
• 
  Edwin Jonk: meta keywords No this isn't being used or frowned on by search engines. Personally I wouldn't use it.
  
  meta description Depends. Meta description isn't being used as a ranking signal. However it may be used as a snippet and thereby the click trough rate might be higher. Therefore, you might want to optimize it for "popular" pages.
• 
  Edwin Jonk: From the expert panel in this weeks SEO Questions hangout on air on 00:48:28 into the YouTube video: https://dumbseoquestions.com/q/is_it_worth_going_back_and_retrospectively_adding_meta_tags +James Hancocks
  
  The cuetimes listed on this page are functional while the live broadcast continues and also once Youtube has finished processing the public broadcast. Processing time varies between 6-24 hours. During this period the clip is viewable in full but the cuetimes cannot be relied on. ;
  
  If our assistance with this issue was useful to you, please consider sharing your success story so that others might benefit.
• 
  John Britsios: You probably would like to try adding meta descriptions to increase your CTR in the search results.