If I could just add a bit more depth to this issue. In the most simple terms. All the time most of us have been with PB mining, we been in a steep rising difficulty.
Until only recently when we have reached this Plato. What does this mean? It means that all this time we have been solving blocks faster than we than what is planned. , therefore payment to miners was higher. Cloud mining payments were higher and happening in shorter period of time. Now with difficulty steady and even dropping miners are sharing less. I've seen it on all cloudmining sites. What I see, and you can see it too on      http://bitcoinwatch.com/      Is on a day when difficulty is on the rise and up into 6 + blocks each hour, your payment will be high, but on a day when difficulty is going lower and networks is only solving 5 blocks each hour your payment on those days will be low, see for yourself on other sites that claim to be mining. A hundred GHS makes some interesting math. each day it pays out, and each day it correlates with the difficulty trend. Not that I'm recommending any of them but the payment is interesting and it correlates with the difficulty. Over all the trend at this plato is low payments.  I don't see this as skimming, I think it is what cloudmining in general is becoming. Hasn't everyone been worned?   don't invest what you can't afford to loose. Have some fun with this but it's not going to get you rich, hopefully you won't loose your bitcoin. It may take a long time to breakeven, maybe this isn't even worth doing, unless you are a bit of a gambler.