My client had 17,500 links pointing to his site from Yellowpages.com and it caused a algorithm penalty to there local search results.  Here is a sample of the links. Now notice that each link contains a different city. My client city is Tacoma WA. We are positive this destroyed there NAP because they went from first place in the Google 3 Pac to not being the Google 3 pack at all, but for the same keyword they are number 3 in organics. When you go to Bing they still maintain there local search rankings.

<a class="sort">Links</a>
http://reliance.yellowpages.com/tacoma-wa/mip/phils-auto-care-8439833?lid=1001611723702
http://solarus.yellowpages.com/tacoma-wa/mip/phils-auto-care-8439833?lid=1001612521758
http://www.yellowpages.com/algona-wa/truck-service-repair
http://www.yellowpages.com/arlington-wa/engine-rebuilding-exchange
http://www.yellowpages.com/arlington-wa/mip/integrity-auto-care-480010482
http://www.yellowpages.com/arlington-wa/mission-motors
http://www.yellowpages.com/arlington-wa/semi-truck-repair

These links are coming from when a business advertises with Yellowpages.com. I have seen evidence that they are destroying one of my clients NAP's because each link is coming from a different city that the local business doesn't belong to them. Have your client Stop advertising with them immediately and disavow all links just to be safe.