Don't do cloud mining, it's all scammy. Best thing is to work for your btc or start buying slowly some btc every month. I've lost money by being a retard and believing in these sites before.
Legit sites do provide mining address and payment proof to the persons who receive payment. They don't need to show payment proof to people who didn't invest. If people who didn't invest want to know, they can get it by exploring blockchain. Ponzis shows payment proof to attract more people to run their ponzi as long as possible and when many invest, mix the coins, send it to a new address and divide it between many addresses... It means its your fault you have to be careful more about that.