1. Hide and bury negative information in the SERPs (search engine rank position)
2. Reduce a competitors website SERP thus improving your own.

Case Study#1:
Sally is a  famous celebrity who has noticed a lot of negative, false information about her life floating around on Internet blogs.  She is very concerned about this information in fear it will tarnish her career.  Sally scrambles desperately to have these negative comments removed by emailing the blog websites but has very little success doing so.

Case Study#2:
George runs a small local dry cleaning business in his city.  He competes with a few other dry cleaners for top spot on Google page #1 but always seems to come up short with a bottom position.  After investigating his competitors offsite SEO he realises that his competition has outranked his site because of spammy backlinks.  He becomes frustrated in Googles desision to reward his competition due to spammy tactics.