I wanted to reach out to other Adsense publisher about the potential downfalls of CDN's especially CloudFlare.
About a month ago I noticed a sharp decrease in my CTR and CPC (nearly 300%!)
Concerned I began scanning my site and noticed numerous blank spaces and 95% of ads being displayed were irrelevant.

After numerous experiment I concluded that the culprit was CLOUDFLARE!
I turned off Rocket Loader/Minify on Cloudfare still was getting blank spaces/irrelevant ads.
I added mod_cloudflare in Apache and still was getting blank spaces/irrelevant ads.
I turned security settings to low and still was getting blank spaces/irrelevant ads.
After numerous failed attempts to correct the problem I decided to ditch Cloudflare and head back to my original Nameserver.

The next day my ads were displaying correctly & relevant to what I was searching.
Since the move back my CPC has nearly doubled & CTR is healthy.

I believe the problem is due to Cloudflare filtering visiter ip addresses.