I believe in what Gavin said on his blog. Most cloud mining services are ponzi schemes. While iim sure that there are some legit ones, i believe by far the majority are ponzis, the top of my list is pb mining.. They dont have any pictures, dont say where they mine, they magically have unlimited amounts of hashing power. My advice is to stay away from them, most likely you wont ROI...
Several of the cloud mining companies have posted in this thread and shown some proof of incorporation and documentation that they are a legitimate company.
The problem with pictures is that I could go to any warehouse that has some nice and neat miners and take a picture and say it's mine. When they run off with your money the pictures will serve as a souvenir to the BTC that you lost. Unless the "company" can prove it is an actual company by showing that it is registered with it's local/state governments you can't be sure it's all just a fancy website covering up a ponzi.
For those companies like PBMining who claim to have a lot of power all they would need to do to prove they are not a ponzi is show their block generation. You can't fake 20PH/s of hashing power on the blockchain. You can fake pics of 20PH/s.
as I used to
