Couple points to add to the discussion.

You really don't want folks clicking your ads because they can't find what they want, you want them clicking your ads because they found what they want, and now they are on to a new search. A good way to check for this is to use a Google search box on your page. If folks are going back to Google for another search, they probably didn't get what they want the first time. You can also provide trackable links. So if on my http://facebook-login-help.com page you really wanted facebook login, I provide a link. Then I can track folks that are in the wrong place (But I haven't hooked up the links yet because the traffic was so low). It's in the publisher's best interest to provide lots of targeted information and be clear and honest about what they are doing. Another good metric is looking at time on site. If the people are only there for 5 seconds, you got a bad visit. If they are there 2 minutes, you must be doing something right.

An ideal page is where somebody is looking for X, finds it, then realize that they need to purchase Y in order to do X. You've provided them necessary information, the advertiser and ad network is providing them the next piece of information on their journey.

If you ask me, the sad fact of the matter is that most folks have no idea what they are searching for. Let me give you an example. I created a site that is related to financial matters. People search for this stuff and come by to visit. I try to provide them useful information.

Now I know from looking at my logs that the most people that click through the ads are going on to Quickbooks, which is tangentially related to the search term but not really. It's as if people were searching for "muffler installation tips" and then went on to click on an ad for car insurance. It's kinda-sorta related. I guess? But at least I can measure it. But I'm really confounded as to the relationship that's happening between the site and the ad. But at least it's something.

Metrics are very important. Without an ad click or some other event, I'm left to assume that you have changed your mind or just didn't know what the heck you were doing and were just thrashing around.

Contrast this targeted approach to my blog, which is just a bunch of stuff thrown together. I get folks all the time coming in on random searches -- bikinis, monkeys, ocelots -- things I've mentioned in a blog entry about something else. But they visit, stay a short time, then leave. If you ask me, these are the people who are truly not getting anything useful at all. At least with the targeted content the publisher (presumably) is trying to help the searcher. These are just random combinations of search terms and content.

Couple other things: first, Google limits the numbers of ads you can put on the page to 3. I personally think 3 is pushing it -- my first sites only had one ad per page. Google was kind enough to email me and tell me that I could put up to three. So lately I've went ahead and put three basically because I'm lazy: I don't want to have to go back and update the site later. Plus it's easier to design for three right off the bat than try to put them in later.

But 1 ad per page and 3 ads per page has a completely different CTR, even though it's the same user, same search, and same types of ads. So unless the publisher is breaking the 3-limit, I think there's a lot of room for mis-diagnosis here.

Second, the content provider has no control over ad availability or scheduling from the ad network. So if you write a wonderful series of articles on polar bears, and there are no polar bear advertisers, you're going to get a bunch of ads that are Public Service Announcements, or are for polar bear ice cream bars, or something else that's a poor fit -- which also decreases your CTR.

I'm not sure any of that helps, but at least it's a bit more information. I know the intent was to look at this from the searcher's perspective, but I think the only way to work towards a solution is to look at problems from multiple angles, and content providers (at least good ones) should have the same goals as searchers.