Link selling is not unethical or unwise.
As many have already said on this page, it is how google itself makes its money.
Google is very broken, in almost any logical search terms users would enter the first few results offered by google bear little relation to the original enquiry. They are almost always dominated by lists not websites.
My first entry to prove this was pet shops in bedford - the first relevant item on the list was at position number 5. I have tried using google many times myself to find things and given up to use an engine that gives better results.
PR does not matter very much, my main site has a
PR of 5 sometimes 4, I get over 5000 uniques a day, of which 80 come from google (on a good day). Many sites come out above me for my search terms most with lower
pr.
Google does not address the things that matter sites using your site name to gain prominence, placing your site name on a landing page 100 times so it always rates above you.
I moved away from trying to please google 3 years ago, I gave up trying to please them after spending over $1000US a month for a year for
SEO's to try and get a good placement on Google. (in this time my visitor numbers went down and my
PR slipped - because we got rid of most reciprocal links (I have re-instated many of them, and they are again the main source of users to my sites, people follow links) I now only ever look at my placement on G or test their results when a message like the one from webproworld yestaerday lands in my inbox.
The stated aim of Google many years ago when they launched themselves was "To do no harm", by their actions over the years they have hurt many small businesses by listing the results badly, hurt many webmasters by changing the way they need to code their pages every so often, and hurt themselves now with their poor algorithms.
Ethics and google should not be used in the same sentence.
Unwise and google are a very good match
David