Cloud Mining can be profitable depending when you get in. Many people who started cloudmining with pbming (like me) in the beginning already reached ROI and now it is all profit. You have to do your own calculations including a little luck based on how you think the difficulty will go (based on new miners coming out etc)
Until PBMining is able to show me their block generation or information regarding their incorporation I'm going to assume they are a ponzi. Gavin labeled cloud mining as such and PBMining's response was to show some pics of a mining center. That doesn't really prove anything.