I've read multiple accounts of how social networking has affected or killed real estate deals.
Imagine the seller that finds a potential buyer's Facebook page stating how they were planning a lowball offer but that they loved the house so much, they'd pay much more. Think that would affect the seller's final asking price?
Imagine the seller who is talking about how desperate they are to get out of their home. A potential buyer (or real estate agent) could use this information to scrape tens of thousands of dollars right out of their pocket.
I had a friend who was recently going through both the buying and selling aspect in trying to upgrade their home. They handled it about as perfect as could be.
They did announce various aspects but kept the details to a minimum.
When they got an offer, they just noted that they had an offer. No details on how they felt about it or whether they were planning on accepting it.
When they found a house they liked, they simply noted that they had a house that fit their criteria, but never announced ‘their love' for any particular house.
Any offers they made simply stated that they were ‘in negotiation'.
All this allowed their friends to see what they were doing and support them in the process, but nothing ever tipped off a potential buyer or seller who might have been rigorous enough to try to glean some details on their thoughts.
If you're ever looking to buy or sell property, assume that every single person that might be on the other side of a potential deal has access to your social networking information. Even if you have everything closed off, assume the information is out there anyways, and put your information out there accordingly.
That one avoided wall post or tweet could save you tens of thousands of dollars.