seoskunk - 11:06 pm on Jun 29, 2012 (gmt 0)
Owner of site A secretly sets up site E and gets some links to it from site D. Owner of site E then disavows those links from site D in the hope that all of the site D outgoing links are discounted thereby harming site B and C in the process.
Your over thinking this, I think if there is a continual negative response to your site over a period of time then your links will be discounted, no single site could achieve this.
I also think this is a huge quality score for the site that links out. Kudos to Bing for bringing this out.
Come to think of it if site A could get links from site D perhaps they wouldn't be doing so bad in the first place!