Like it or not, link building has been and still is big, big business. Doing it well takes a lot of time and resources, which means that many webmasters/site owners can’t or don’t want to do it themselves. Many agencies that handle other aspects of search engine marketing want to outsource it simply because of the massive resource drain.
That’s great news for people like me who specialize in link building but the intense supply and demand nature of links coupled with the ease of promoting yourself through social media have led to a frightening increase in people who build bad links and really have no idea what they’re doing
http://searchengineland.com/50-things-every-link-builder-needs-to-know-129580
