i think this one's okay
they get the money from all the adverts on the site and all the adverts they can email you, but if you don't mind that it's not so bad (though i haven't actually done it yet)
though, they can decide to not give you a free thing for any reason they see fit pretty much and suspect you of anything
but it's not a virus and, if they don't cancel your account, you can get something for 'free'.
you just have to get some other people to join it too