Using real estate websites using porn style recip link trading as an example...
"During the chat, I referred to this thread at RealEstateWebmasters (14 pages and 132 replies) discussing the "shot across the bough" that Matt's team fired in mid-May. Obviously, that site has long recommended link exchanges as a way to get ranks, and honestly, it's hard to find fault with their advice since until just recently, the tactics were very effective. Here's how it usually works in the real estate website world:
A new realtor launches her site and finds that Google traffic is the best thing since sliced bread
Naturally, wanting more, she starts reading online about how to get Google rankings to real estate websites
Many of the popular forums & guides suggest forming relationships with other site owners in the real estate world and trading links
Our realtor takes the hint - she works in Bend, Oregon, so she contacts site owners from Poughkeepsie to Puyallup seeking link exchanges
Each site places a link to the other on a "links" page (a good example would be this one from a Missouri real estate agent)
Our realtor gets a bit in rankings from the link love and she's thrilled
Matt comes in and ruins her day

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http://www.seomoz.org/blog/how-to-ha...of-real-estate