There are these things, that just make you want to facepalm and today was ripe for that experience. What happened? Well, I was reviewing the ad targeting of several pages on this websites, which were not performing too well CTR wise. By doing so, I came across one, which has computer games as topic, but strangely only showed programming related banners. I checked the text several times. It had all the keywords, MMORPG publishers should target, but nevertheless the ads were always about Java programming and even removing several phrases, that sounded like they'd be of interest to suppliers of software development tools, would not remedy that. In the end, the only Java related terms remaining pretty much was "JAR", but the intended banners still did not show up. Could "JAR" really be such a strong keyword, that it would overrule any gaming related keywords, which were by far more numerous on that page? I checked the page in question using Google's keywordtool and indeed there was a strong suggestion, that Google considered Java programming to be the correct topic. Bummer!
It took me quite some time to come up with the obvious idea, which of course is not only to proofread the text in question, but actually do a full textsearch over the entire page. Talk about wasting hours for searching in the wrong places. The tag cloud in the navigation sidebar was happily feeding all kinds of inapproriate keywords to AdSense and since it's HTML code is placed above the main content area, it's keywords naturally have a stronger weight. Combine that with the fact, that ads for software tools usually pay higher than those of online games and you have your mystery of ill targeted ads explained.
Lesson learned: When using a CMS, always edit the theme template file and put
tags around the page navigation. Or at least make sure, to put the page navigation's HTML code below the main content area (and there I always wondered, why wordpress has it's sidebar on the right).