Cloud mining is what's called a confidence trick. Apparently many people aren't aware of how that works so here's a wikipedia article:
https://en.wikipedia.org/wiki/Long_conBasically they gain your confidence by giving you regular payouts, if you're lucky it will be close to what you first put in, and then once they have gained your confidence, you will be eager to invest more, which they can then use to pay off new users (some of whom you probably bring them by referrals ) until they reach what they consider to be a nice amount to run off with. The longer they keep the con going the more they can make off with in the end. Almost all of these operations are run by people who will never reveal their identity, won't show pictures or any sort of proof that they have mining equipment, and if you question them a little to look for proof, they will probably just say something to the effect of "well everyone whos already with us is getting paid and happy so if you don't trust us you are free to go elsewhere, we don't really need your business". PBMining is a great example of a well executed and still running longcon (i don't expect it to last 5 years, but if they do good for them) , Markets.cx is a not as long term example because it only lasted a month or so, but it's operators still got away with lots of money without ever having tor prove who they where, or that they had any equipment, they just said "we're cex.io for litecoin" and people hopped right on in thinking they would trade ghs (or mhs i suppose) and get a great deal... nope Chuck Testa.
Cex.io is probably legit in the sense that they have hardware. You can even redeem it from them, though i imagine anyone who is willing to pay such a premium has no idea how to actually use the hardware if they got it. So their confidence trick isn't so much about running off with peoples funds, but getting those funds so they can buy more hardware to use for themselves. Which is a pretty honest con, but still a con.
If you really wanted to mine without having your own hardware, the best options out there are to rent hashing power directly from intendant miners, who sell them on markets like
http://nicehash.com and
http://betarigs.com. These services allow you to rent hashing power for hourly, daily, or weekly shifts, So you don't have to wait a year to see if you'll profit. You'll still have to pay what the market price is, but its usually fairly close to what they would be expected to earn back in that time period and you're buying it is more to lessen the risk of the miner whos selling it (because you can earn more or less than they would depending on what pool you use and how lucky it is that day). You won't make a living off it, but you'll probably make a small profit if you have patience and buy when the market rates are lower. I don't call these services "cloud mining" because you actually get control over what pool they mine, and you are usually renting from independent mining equipment owners and smaller farm operations, and that sets them apart from the cloud operators in my book. They are just "rentals" like you could rent a car or a truck, use it for the day and then give it back. If you keep renting cars all day every day its way cheaper to buy a car, but if your just looking to move a couch over the weekend its probably a better idea to go to uhaul instead of a dealership.
TLDR: try
http://betarigs.com, you can test them out for a day or less and see if you make a profit, and if you don't that money at least goes to an independent miner somewhere and you aren't out a whole bunch of money.