From
http://faucet.bitcoinzebra.com/payment:2016-01-23 IMPORTANT INFORMATION ABOUT THIS WEEKS PAYMENT RUN
On Thursday 21st January we were advised by Google that our AdSense account has been disabled. As you are probably aware AdSense is our highest source of advertising income, and the timing of this means that we will receive no revenue for the AdSense ads shown on Bitcoin Zebra for the whole of December 2015 and so far in January 2106. We are not the only major faucet that that this has happened to - you may have already heard about others that have suffered the same consequences. We have submitted an appeal to Google and we are speaking to our AdSense account manager to try to get to the bottom of why this happened and how it can be resolved.
There is no denying the fact that Google blocked adsense accounts of some of the high paying faucets. Moonbitcoin is displaying google ads again, maybe they sorted out the issue with google (earlier adsense ban means you are banned forever, now your adsense account only gets deactivated, you fix the problem, apply again, and everything is back to normal again) or they bought a new adsense acccount. I just created a post on my blog regarding "how to start a adsense friendly faucet",
http://bitckerz.net/google-adsense-faucets/ (not spamming or promoting my blog, it just have the basics, thought might be helpful to some users)