In the past there were many Cloud Mining services available. Some of them are legit, but some of them are Ponzi scheme or other form of scam.
Unfortunately Cloud Mining services can be easily exploited as user can't have enough control over the service. Be very cautious about investing in any cloud mining now.
Cloud minng is difficult for customers now. The difficult will rise a lot with the new Bitmain S7 and Avolon A6.