I assume that if ads are blocked, they do not show as ad requests and will not reduce CTR.
I would also sumise that those that now block ads would not have clicked on them anyway - so CTR may be improved.

I thought that the ads are blocked from loading on the page but the request is still sent to the servers?

The assumption that those using adblock would not have clicked any ad anyway is disputable. Maybe the user intention installing adblock was just to block those popups, interstitials, those 5secs ads in youtube videos? Not possible to know.

I'm using a service called PageFair (no affiliation). It helped me measure how much AdBlock was going on (about 33% on my site) and allows you to run text only ads you can create and are displayed despite of ad blocking (they're part of the Acceptable Ads programme).

So they reported that 33% of your users uses adblock and they sell the solution to you, really?

I visited the PageFair site and honestly, their ethics are very questionable, with a graphic showing a site with more than 22% users using adblock, big headlines showing 70% increase in adblock usage, etc..

Also this solution is just creating another problem.

Not sure how effective their adblock detection is, it looks like a small javascript file but it's minimized and I'm not very good at it.

The trend is clear (despite the fact Adblock is not trustworthy any more): [goo.gl...]

I'm not sure how to read this graph; hopefully Feb 2013 wasn't the peak of online advertising...

Adblockers (like adblock or noscript, etc) block third party, popups, js scripts, etc. That user will never see any ads and thus cannot be cataloged as other than "not there" as to stats. (Note: This is the way I personally surf the web. That "other machine" used for testing lets all that stuff come through),.

What is more realistic is the economy, worldwide, and present trends looks to continue dismal for some time to come.

To avoid these add-ons and plugins shift part of your ad inventory to direct (ie. hosted on YOUR site) and that 3.3% might become a more positie number.

I had hoped that someone would come in and confirm whether ads blocked by adblock still show as ad impressions in yur adsense stats.
I did some more searching and the consensus seams to be that they dont - IncrediBILL made the point in this thread back in 2008:
[webmasterworld.com...]

That figures, my CTR rates have increased during the past year. Compared with CTR when I first took up Adsense the improvement is from "totally pathetic" to "pathetic" but it has still been a move in the right direction.

the fact that the usage of such software is growing exponentially.

Maybe I lead a sheltered life however I do not know of anyone who uses such things and I get to repair a fair amount of computers as well as discuss people's usage of them.

IMHO ad blindness, subliminal ad blocking might be a better description, is the major reason, I know I do it and I know lots of other people who do it.

That's a strange chart Selen has given. if I read that correctly does that mean 100% of Poles have ad blockers?

Then how come Kraków has 100% and Warsaw 76%? That's not 100%!

IMHO ad blindness, subliminal ad blocking might be a better description, is the major reason, I know I do it and I know lots of other people who do it. 

Exactly, this is just the maturing of the web. Users are learning what ads look like and how to automatically ignore them. Make the ads not look like ads and the ctr goes up.

Exactly, this is just the maturing of the web. Users are learning what ads look like and how to automatically ignore them.

I think a lot of ad blindness is caused by ad excess. My local metropolitan newspaper, for example, has seven ads on a typical news page. Is it any wonder that people ignore the ads? Especially when they aren't researching purchases and/or the ads don't solve a problem for them?

Another factor might be that the public is getting spooked by the ads that follow them around. I have heard people accuse the website of spying on the user because of the ads they keep seeing.

Another factor might be that the public is getting spooked by the ads that follow them around.

Good point. And even if they aren't spooked, they may just tune out such behavioral ads after a while.

Each new workaround for ad blindness probably has a limited shelf life.

I think a lot of ad blindness is caused by ad excess.

Absolutely correct and talking of newspaper sites, for me they are the worst of the worst when it comes to the page settling down after all their various ad suppliers have finished loading...after 30-60 seconds!

Some of them are so bad I refuse to go to them any more and they are well-known international names.

I use a 1.66ghz acer aspire netbook connected to a monitor in my coffee room to check out the news and most of those news sites are unusable for me. Like you said, takes minutes to fully load even with Ghostery blocking a lot of their ads and trackers. (50+ 3rd party calls in some cases.) When it all finally settles down to the point I can read it, some mobile widget reloads the page and it starts all over again.
Scroll down a bit and more crap loads till the browser eventually locks up.

If there's More than 2 or 3 ads on a page, I don't even see them. It's just carnival clutter to me.

Scroll down a bit and more crap loads till the browser eventually locks up.

It's interesting how some of them can make their mobile sites load properly!