Search algorithms & popularity factors: link, social, click, blog, industry. Since modern search engines are concerned with popularity and not direct relevancy, & big firms up the price of text link buying beyond affordability...
There's clear demand from searchers who increasingly expect user reviews as part of their local search experience. Social and local search are on a clear path towards merging.
K. Sonawane, B. Wagh, M. Shelar, and N. Yeole. International Journal on Recent and Innovation Trends in Computing and Communication, 3 (1):
280--283(January 2015)