Are they trusted?
Yeah they can be as I have also used miningrigrentals few times before to rent some mining rigs to mine new coins on early days.
How is their paying rate per 1 kH/s?
Paying rate? They are not cloud mining platform. You can rent out your rigs or can rent some rigs to mine coins you like. Obviously you will not get profit with those rigs if you are only willing to rent them to mine bitcoin, ethereum like coins.