Except ask yourself one question.  Why would any honest actor provide this service?

Let's say the provider lives in an area where he is allowed to steal electricity from the local taxpayers (artifically subsidized power costs, such as in China or wherever).  Let's say the provider has the hardware to actually do the hashing.

It's clear that a dishonest provider could run a scam by renting out hashing power for more than it earns.  But assuming the provider is honest, under what circumstances would it be more profitable for the provider to rent out that hashing power than it would be to just use it? 

... crickets chirp ...

That's right!  No circumstances at all!

Making a deal with someone who makes less profit in that deal than s/he would by not making it, is asking to be ripped off.  Because it's dead solid that no such actor would be there if they aren't trying to rip you off.