I have found that it all depends on the AHJ and the District attourneys. In places that only want a permit fee, it's not worth the time or phone call to report them. In juridictions that will ENFORCE the laws with heavy fines and jail time, it is worth the call.
It's really quite intresting to here some of those fly by nites telling each other what places to avoid.
By the way, just had a so called GC ask me to hook up the panel for a house. He claims that all the material is there, all the circuits are run and he only needs a licensed electrician to hook up the panel so that the inspector will pass the house.
He also told me what he wants to pay and no more.
I hope he finds a sucker - I'll guarentee he will not like my price.