Panthro - 5:10 pm on Jul 6, 2011 (gmt 0)

2 - are so dismayed they immediately hit their back button, suddenly popping back onto our radar, alerting us to the fact they were displeased with the result we just showed them - why else would they suddenly come back, without consuming your content? Displeased.

That is a bold assumption to make. Do you really think there is NO other explanation? As discussed all over these boards, this is a dangerous metric to use when determining a searcher's satisfaction with a particular page for a particular query. I often search for information, find a list of pages for my query, click on one, see the phone number or other information I'm looking for and get right out of there. Other websites have contact forms on the destination page that only take 20 seconds to complete and then the user is done, they have found what they want or accomplished the task they set out to accomplish. Hiding web pages that efficiently provide exactly what the searcher is looking for is a terrible way to provide excellent search results. The opposite can also occur - that webmasters will be encouraged to build pages that are always at least 1 step away to keep users clicking.