What should I do with comment spam?

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

• 
  Laure Sabini: Hi everyone,
  I'm having a hard time deciding what to do about this case of 'bad backlinks', I need your help.
  
  This is what's happening:
  - My client's rankings has been decreasing for a few months but is now stable - about page 8 for main keyword,
  - I noticed bad backlinks from 'ok' websites in the comments area.
  Most of these websites are indexed in Google and seem legitimate. But that's in the comments that there is a problem: hundreds sometimes thousands of comments have been added, often using keyword anchor text, but they're all not related to my client's industry. Comments don't add any value so they're all poor quality...
  - These backlinks come from divers language websites like English, French, Chinese, hungarian...
  - Last but not least these links are added one or 2 at a time, weekly :(
  
  That being said, the websites themselves don't seem bad. It seems these websites were 'hacked' in the sense that someone or something added these comments knowing that they wouldn't be approved. And these comments link to hundreds/thousands of divers websites that didn't ask for these links.
  
  This is an example of those sites:
  http:// palermoslafamiglia dot com/stone-baked/the-messina dot aspx
  
  The dilemna here is that I don't want to disavow these links because I don't think the webmaster of these websites is even aware of these comments. And because these bad backlinks are added weekly, it doesn't seem this will ever end up...
  
  I hope this makes sense and that you can tell me what you think and maybe some solutions...
  Thanks a lot for your time.
• 
  W.E. Jonk: Your post was flagged by Google+ as spam and I approved your post. However can you disable the link like: ;http:// palermoslafamiglia dot com/stone-baked/the-messina dot aspx
• 
  Andy Wigglesworth: If you feel that bad for a hacked site owner and don't want to disavow (has your client had a penalty through webmaster tools?) - then try and contact the owner of the hacked websites and let them know - if you don't get a response, disavow all the way and sort your clients website out
• 
  Laure Sabini: Thanks W.E. Jonk, I've updated my post.
  
  Thanks Andy for your take.
  Yes I've started emailing the webmasters of these websites. My other concern though is that these bad links are added weekly...
  The other idea is to use another domain name my client bought even before the domain he's using right now (but no keywords in domain). I'm afraid to lose ranking again though, even if we can change most of the links from directories/social medias/ articles WE asked...
• 
  Brent Wildman: +Laure Sabini ;If all these comments are being posted weekly, it's a pretty good probability that there's a script or programming that is generating and posting these comments to whatever blog it can scrape.
  
  Unfortunately if you can't stop this person or program you will be constantly fighting this and may never recover your previous rankings.
  
  I suggest using the new domain name. Exact Match Domains are starting to carry less weight so I wouldn't worry too much about that.