I have trouble with statements regarding targeting. The thing is that the targeting is very dynamic and dependent on a wide variety of factors, thus it is difficult to get a a good picture on a how successful or unsuccessful it is. The one factor that may contribute to what you are seeing is the ratio of contextual to interest based ads served. If Adsense is serving more interest based ads then the there is greater likelihood of seeing mismatched ads, this is specially true if your are viewing the sites incognito with a cleared cache.

I was working on a new site today, one that only exists on my localhost. I added ad code to the pages and the ads were appearing and they were surprisingly relevant to the page content. Content that for all intents and purposes does not exist as it can't be crawled. I am assuming that the ads must be served based on my browsing history, but who knows.

As for the drop in click through rates, I am seeing a similar thing. But I am assuming that this is due to other factors such changes on the clickable area and other similar factors implemented to reduce invalid/accidental clicks.

Yes well, revenue recovered today... I did nothing significant except added content to three webpages of (30,000 + page website). Most of the better crocker and hotel ads went away..

AdSense appeared to have been broke to me...

The one factor that may contribute to what you are seeing is the ratio of contextual to interest based ads served

I believe that is larger factor than perhaps we might imagine. I have been saying for ever since those ads came into being that they are all too often totally pointless.

Over 90% of AdSense ads I see on sites I visit are ads for items I have either purchased on eBay, or have placed on my watch list, or from my trusted suppliers. These sites also are sites nothing to do with my recent purchase of an all singing, all dancing CPU.

The hysterical part is always, every time, without fail - the part offered in the ad will be priced between 25% to 100% dearer than I had already paid.

Pointless, the publisher would never get a click, except from the less discerning buyer.

But, Mr.AdSense and others swear by IBA - who am I to disagree? The hard part for the hapless publisher is they have no real control.

Yesterday! Imagine one or more AdSense ads from PC suppliers for an Intel i7-6100K CPU on a recipe site when searching for a "Coffee Cake" recipe.

The recipe was 'triffic, the CPU beyond my budget.

ratio of contextual to interest based ads served

I can assure all that my browser does not have any recorded history of Food ingredients, Recipes, Cars, Bank Checking Accounts, Music Festivals, etc..

I do a lot of boat searches, fishing reports, Stock Market related Websites, Facebook, etc.. I don't think I have ever seen interest based ads on those topics shown to me on my website..

Something was broke, configured wrong, database lost - who knows... I did send a screen shot of the increased ad impressions + CPM drop to AdSense Support. Nothing back so far..