The reason Pink and Paul Fredrick advertise on AAAC is because they are affiliate type advertisers and didn't ask to be there. They're probably not getting a ton of business through Andy's links, but as you said, random visitors may show up for some advice and click on the ads, you never know. I think I still have a Pink banner and maybe a Paul Fredrick banner here, but I don't think anyone's ever clicked on them.
We/you guys do constitute a very valuable and hard-to-reach demographic for potential advertisers, but as you said, it's hard to keep a balance where we try to maintain the impartiality in opinions that is the soul of the site. If we started adjusting our opinions or steering discussions to reflect advertisers' wishes, it would (and should) turn off the core members who make this place so helpful.
I have been approached a few times about selling the forum, but I've never seriously considered it except as a thought exercise. I enjoy it too much and would worry that it would become like some other forums where you can't read it for the amount of advertising all over the place and it kills the atmosphere I've tried to create and maintain.
Also, a more general question: when people talk about the "worth" of a site, over what time period are they thinking? With the proper direction, lots of pretty basic sites could be worth a ton of money if they were grown correctly over 5 years. Is it just like buying a restaurant or something, where you pay for the infrastructure and hopefully some client base - is the value reflective of the potential profit over a year, five years, ten years?