Banner blindness generally only becomes a problem if you have continuous returning visitors, for example a forum of which members visit daily would suffer from banner blindness which is why you see adverts being moved slightly every couple of months or colours changed to bring that distraction back into play.
In the broader spectrum adverts if anything have become more accepted as apart of the furniture, that in its self maybe seen as a banner blindness but again only in certain situations/scenarios .
Whats more to blame ( but not the sole point ) is the fact Google has become increasing good at reducing junk , fraudulent traffic and clicks to its ads, its changed the entire structure of how ads are shown to people on a massive scale, for example showing people adverts of a large percentage based on their previous visits and search trends rather than being based on the content of which the site they are visiting at that moment.
Then you have smart pricing for the lower quality of site, lower quality of traffic and visitors.
With all that said, in some niches you still get hit hard. 5 years ago i had a couple of sites in totally different niches, both generating 4 figure sums on a monthly basis..............over a 12 month period you could physically see the decline of revenue to eventually around 50% , even though the sites were better than ever...we kept up with standards, traffic from core premium advertising lands such as US,UK, GER etc were rising at a significant rate................................yet still a 50% cut within 12 - 18 months.
So much so it was actually more beneficial to sell direct adverts even with the extra leg work of adding ads and contacting potential advertisers.
Not to mention the conspiracy theory's of Google Wacking publishers that get close to the Golden numbers doom. Im sure you all saw the Leak which was "supposedly" pretty accurate from last year :
http://pastebin.com/qh6Tta3h ............interesting reading whether its true or not.
