I think cloud mining sites are not a scam but HYIP's. If any bitcoin website offers a ROI under 3 months it is most likely not going to last very long. All the double your money websites those are scams and not even a HYIP. I like to invest in new cloud mining but i only invest in the first months then wait for my ROI and when ROI then that is profit. I did fall into scams like someone mentioned in this thread, it takes a year or a bit more then you understand how it really works.
Gambling is not better then cloud mining, in cloud mining you have a low risk for 4-5 months then its high risk while gambling you are always risking, who ever made lots of money gambling? honestly before losing about 10 times the amount you won? Now that is scam.
Another example is scrypt cc, boy did i ever make money on that site! First year I cleared about 1.5 BTC with about 0.25 BTC to start, of course this was with the help of trading, the. I withdraw my coin for a while invested in a safe place for 4-5 months then i saw the site was still going strong and paying so i decided to give it a shot, put my 1.5 btc back into it made it up to 2 BTC in about 1 week of trading (they used to havle).
Then after one week winning 0.5 btc I thought this must be my lucky day so i withdraw all in one shot 2 btc and it never got throught, never returned, support never contacted me back.
I was interested in cldmine then topmine but they offered similar rewards so i do not trust topmine since cldmine closed. Now I am trying minerfarm and cloudminergame, so far they have been paying only minerfarm seems to be getting trouble, hopefully it gets resolved soon.
Anyways just some thoughts I had.