One cloud-mining I've seen was Genesis mining, it offers a two-year contract worth 30$ for a 1MH/s, 869$ for 30Mh/s and 2799$ for 100Mh/s.

Now by using 869$ @ 30Mh/s and 2.07$ per day mining ethereum (rate from whattomine.com)

869$/2.07$ per day = 420 days to make ROI

365 days * 2 years = 730 days - 420 days = 310 days for profit

310 days* 2.07$ = 641$ profit for a two year contract

It maybe a good investment, no hardware/software troubleshooting and no electricity cost in mind just pure profit, give them the money and you wait for two years for your profit.
The only risk I see here is when genesis mining turns out to be another ponzi scheme which is unlikely, then they can take away all your investment.

But for me I will go with building a rig an then mine alts on my own.