Does Google AdSense work better on text-based pages?

You're in luck! You are right in this instance, and the reason is logical if you think about how advertising contextual analysis systems work. In a nutshell, you "give" a page to the ad network for matching up with a keyword or set of keywords and it then scans all the content doing a keyword density analysis.

That doesn't work if there aren't words there, does it?

In fact, if we pop over to the Inside AdSense blog that's actually run by the Google team, you'll find that they just recently wrote:

"While we’re constantly working to improve our targeting technology, our crawlers need text to properly match ads to your pages. Although images, flash, and streaming video can help spice up a site, relying heavily on these sorts of elements will make it difficult for us to get a good read on what your site is about."

I want to go back to keyword density for just a second too as it's a very important topic and one that should change how you write on your own blog / create the text for your Web pages.

Go back and skim the words I've used in this blog entry so far. You'll see that some words don't show up at all (like "baroque", at least until I added it there) while other words show up a bunch of times (like "AdSense"). If you were to count all the words on this page and then do some simple math, you could calculate word frequency (which is really the same as word density). If AdSense shows up 13 times in this article and there are 310 words total, that means "AdSense" has an 13/310 or 0.04 density, while the other word I mentioned but am only going to use once is 1/310 or 0.0032 density.

It's straightforward to conclude that AdSense is a dense keyword and therefore a better target for matching ads than, um, that other word. :-)

If you only have seven words and three complex flash animations, well, you can see where that becomes a very difficult page to parse and analyze for Google or any other contextual ad engine.

So, yes, you won this argument. :-)