Unfortunately, your belief that this is a scam is not enough - if they are really giving the prizes advertised, by the methods stated, it's not a scam.
I'm sorry you felt misled, but I suspect that you haven't taken any significant action or incurred any significant costs because of the "misleading" language. This means that you have no damages, and therefore no basis to file suit. Just delete their emails with the rest of your spam.
A number of state attorneys general have sued PCH over the years. Their language is pretty refined at this point to be legal. They do in fact give out the grand prize to people, although the odds of winning are incredibly low. Doesn't sound like much of a case to me; however feel free to contact your state attorney general and register your annoyance. That was enough in NY to get their AG to sue. Best of luck.
The author is a Maryland attorney; however no answer given on Avvo is intended as legal advice or intended to create an attorney-client relationship. Dan's expertise lies in the electronic entertainment (video game) industry, as well as complex internet law issues, electronic free speech, entertainment law, copyright and trademark law, and computer fraud. He primarily represents game developers and founders of emergent internet technologies.