Addendum - On Friday and Saturday my email volume was almost zero even from spammers and I'm used to getting hundreds a day. Why that would have anything to do with AdSense I have no idea but it's rather coincidental.
Updating my situation. Yesterday was an earning which is normal and what I expect to see daily. However, the days starting April were horrific. This isn't a traffic loss issue. There is something more to this imo. I wonder if there is such a thing as spam ads. In effect, my site was showing rubbish to the point that Adsense earning appeared broken. It's either that or the ads were slow to load. I haven't heard theories about ad displaying issues, but that may be another cause. When looking at my site briefly, I was suspicious about ads load time.
Yahoo/Bing is probably taking away Google's revenue and we are getting hit.
Not in my widget sector, hardly anyone is using YahBing. Talking to people globally in my industry there is a general malaise and despondency about the future, many long-time advertisers are no longer doing it therefore the bidding price goes down.
Nice couple days on weekend. Monday was a near bottom out total, and total is moving like a slug. I'm going into my ads and blocking. I can't think this is anything else. There must be some type of ad spam/junk ads showing up in big volume which is choking off my earnings. I don't normally see such a drastic weekend to weekday dropoff.
Yesterday, with a normal traffic day (99.9% US visits) and a normal amount of clicks, the main site brought in almost double the daily average of the last two months so CPC was obviously high. Again, I'm going to chalk this up to more locally-targeted advertising on this site generally.
@Redbar -- I'm not sure how a site that attracts visitors from every corner of the planet is going to be seen as a target for local ads from anywhere and this MAY BE contributing to the differences in results we are experiencing. It's not possible to narrow a site's focus in every case but just as niche is a type of focus, so is geography. If, as I suspect, that local advertising is driving growth on my main site, then I attribute that to the continental geographic targeting the site enjoys (thanks to the many many hours of programming, configuring and content shaping it took to achieve).
I'm fairly sure that you are correct, Google seems to be having a major issue with local v int ads therefore has Google now become the local ad centre whereas it used to be international?
Certainly there are widget advertisers who use global and I'm pretty sure that local is working reasonably accurately in some countries, and where the advertiser has AdWords sussed, and isn't advertising to all and sundry.
It is very evident that for many, many countries I have never, ever received a single click even when I have had thousands of PVs from a country over the years G has been supplying that info.
At times G just seems to be hell-bent on banging more nails into their coffin lid for some widget sectors and is very apparent when reviewing their financials for publishers.
I had an OK month in March, better than Jan, Feb but April has been absolutely brutal 41.4 % same day below March and March wasnt even that good, was about 25-33% below what I was getting last year... CPC seems to have dropped and CTR for me.
Fridays are rapidly becoming my worst day of the week, this will be the fourth in succession, PVs so far ~33%, clicks ~20%, CTR 60%, CPC 68%, RPM 41% & Earnings 14.8% ... Diabolical, where on earth is all the traffic?