But I'm worried.

My ads may blend too much. Though the CTR has increased substantially, it's still lower than 10%. I know a lot of sites with CTR around 10% which is normally not that big a deal, not to mention some extremely optimized adsense templates with 20% CTR. But I'm still worried about how Google sees this.

It's very contradictory of them to teach us how to position the ads in ways such as the heat map to generate more income while banning people who send poor quality traffic to adsense ads buyers.

Well my worry is this:

Let's say you are a fresh adsense publisher and just implemented a 336*228 ad slot on your pages that are very rich in original content, top quality. You don't know jack about optimization. The CTR is merely 1%. Very humble beginning and we can be sure those who click the ads are very interested in them. Both Google and advertisers love it because you are sending quality traffic.

Then you learned at DP about how to increase CTR by blending the ads into content - ahhhh, this is the trick, what's blending? Actually Google also offers to help on increasing your earnings in regards to places to put your ads, color palettes they recommend and more. In short, blending is just another way of saying trying to make the visitors believe it's the content rather than ads. It may have many degrees but don't you agree? Try making your adsense ads distinguishedly bordered with a top lable of 'Advertisement' and see the CTR decrease dramatically.

So you have implemented the changes - removed the borders, blended the colors and moved the ads to the most noticeable position according to the heat map. The CTR soared to 4%. Now my concern is that if the extra 3% traffic we are sending are quality traffic? Because of the changes / optimizations we have made in the hope of increasing earnings - blending and repositioning the ads, the extra 3% visitors may not be as interested in the ads as the first 1% are, don't you agree? They traffic quality is diluted.

Google may treat us in 2 ways:

1. Lower the eCPM to justify the traffic quality and protect adsense advertisers.
2. Ban us if the traffic we are sending is extremely crap - either you are buying tons of crap traffic or you blend the ads too much that visitors thought it's just your site content rather than some commercial parties trying to sell.

Therefore, I come to my points:

1. Google is weird and moodiness. Never give them a chance.
2. Do a few optimizations but not much. Believe it or not, outstanding label of 'Advertisement' may increase your eCPM because the traffic you are sending are aware of the ads and ready to buy, knowing what they need. And tricks like these should actually be avoided if possible - even adsense team approves them, I'd still steer clear of them.
3. Increasing CTR should not be the No.1 way to increase your earnings. I know, it's very tempting and can double your earnings overnight. But it never runs long-term. They'll sooner or later justify the traffic your are sending and decrease the eCPM. Plus, it's dangerous and may get you banned.
4. Sticking to writing great content rather than playing tricks on adsense to increase earnings.

Just my 2 cents, please correct me if I'm wrong and provide your opinions.