They one of the few real company's.
It is not a scam, but like Hash Flare the ROI is volatile and Genesis Mining themselves in accordance with their terms had to cancel many contracts due to unsustainability and this is why people marked them as a scam. These contracts usually show returns on month 16 and a lot can happen in 16 months. Currencies which has doubled in value like ZEC and ETH, well, that is now viable again to cloud mine.
Hash Nest is legit. The PACMiC mining contracts has consistently returned 10-15% p/a. Plus, they pay out bonusses. Like the abovementioned cloud mining entities, these contracts are cancelled once they are unsustainable. Then you can also buy and host Antminers through them, that is whether they have stock and we are already closing in on GHS 5.0, and the reason why I’m stalling on going ASIC now. You can withdraw you Antminer anytime, and when the Antminer is unsustainable you will need to promptly withdraw.
The other day I rediscovered my Eobot account that I have created in 2013/14, many regard this as an outright scam, but I managed to withdraw everything that I had mined with them. Are they a scam? I don’t know. It is all about sustainability.
All-in-all, I have mined with all entities named above.