Companies that offer this service: Hashflare, Genesis Mining, Minex, viabtc, antmining, hashnest. Some of these companies are known for their pools, for their mining-related products, and for their large mining farms.
But there are several other small businesses that are offering such services. My question is: Is there any checklist to check if it is a legitimate business? Could I ask to receive Bitcoin directly from a newly generated block? Could I request that the blocks be generated with a contract batch signature? Are there technical possibilities to ensure that they are actually mining Bitcoin rather than managing a Ponzi scheme?
Yes there is site in online to find the best projects and to confirm whether it is legit or not scammy one. Please use the below to find it dude.
http://badbitcoin.org/thebadlist
If you want to block these kind fake site ads while you browsing there are add ons in the Google chrome.
Install and enable that to stop the spammy ads.