So I started up this online encyclopedia, which I think is a nice thing, some value added, and I put up relatively discreet AdSense ads (horizontal text-only with invisible border and background matched to page, only a single block), and, as I saw my impressions finally start to climb as G got some pages indexed, I began to drool. Well, I wiped the drool when I looked at the AdSense reports. The AdSense ads there are at a CPM barely over 6 % of the cumulative of my several other quite various (and not especially targeted at lucrative markets) sites. (Boy, I wish we could talk actual numbers.) The reason is not far to seek: whether the page is on carrots or doctors, movies or personal computers, the ad block is always the same four comically irrelevant ads, a typical representative being the one offering medieval crossbows. Well, hey, medieval crossbows are hot, right? And relevant? Wow: if you're a doctor, you can shoot a carrot with your midieval-style crossbow while making a movie of it to watch on your personal computer. Now I get it. Can anyone guess as to just exactly at what point--if ever--G might condescend to serve any of its famous relevant ads, so that I can start to make some pittance off AdSense?
Sometimes...never. Other times, soon. It's a bad answer, but adsense can be quirky and frustrating. Sometimes, once it latches on to what it thinks is relevant, it stays that way for a very long time. Other times, it quickly reverts to serving relevant ads. You can try excluding particular ads and see if that helps. Again, sometimes it does, sometimes it doesn't.
I clicked on a few random links and this one showed different ads ... but I see the 4-block you are talking about on your pages - sorry, I'm not in the market for crossbows, but I WAS kinda curious to see what it was about, so I clicked thru for 'ya ... ;-)
I have, on consideration, realized that AdSense does not, when called, scan the page for content--it apparently relies on Google's mainstream indexing, caching, and whatever they do about relevance for a page. An unindexed (by G main) page will, I guess, be just a mystery to AdSense, so they will serve the cheapest ads they have (though why, then, we ever get PSAs I don't know). That is, to put it mildly, bizarre. A naif might think that whenever AdSense is called for a page not yet indexed by G, that G would at once index it--maybe not quickly enough to respond to that very call, but very soon thereafter. OK, that would be a way for a modestly clever operator to "force" pages into G's index: and? G's nominal goal is to index the whole net. Surely pages on which potential customers of G's actual customers are looking for ads about those customers would seem natural candidates for indexing. If that "jumps" them a bit ahead of their schedule, precisely whose nose is the skin off? But children will be children . . . . (Yeah, I'm dissing G.) Ah, thankee kindly, sor, thankee (would tug forelock, but forelock is long since gone).
Actually, it has been my experience that if you add a NEW page with Adsense Ads ***OR*** add Adsense Ads to an existing page, you will be paid a visit shortly (within minutes) after you first view it by Google's Mediabot. This IS the way it uses to classifiy a page ... but it is NOT GoogleBot for the SE stuff.
If I am understanding that aright, one could assure that all one's pages are processed by AdSense by simply sending a robot round to "view" each. (By "processed", I mean digested in whatever AdSensish manner would allow serving reasonably relevant ads on the next access.) Is that a valid interpretation?
Sometimes...never. Other times, soon. It's a bad answer, but adsense can be quirky and frustrating. Sometimes, once it latches on to what it thinks is relevant, it stays that way for a very long time. Other times, it quickly reverts to serving relevant ads. You can try excluding particular ads and see if that helps. Again, sometimes it does, sometimes it doesn't.