Besides the fact they nobody knows what is being done behind the scenes to ensure results are (or aren't) fair, using a sample of individuals that are all attempting to play the system against each other deeply and irreparably biases the data.

On top of that, jokes like the one I responded to and comments like yours only serve to legitimize a "service" thats sole purpose is to squeeze every penny from its users. It doesn't provide anything beneficial to anyone but its owners.