By that definition, casinos aren't scams: they are quite honest with the "house always wins (but we'll make sure you're having fun)" business model. The gender prediction would be, because this guy knows he's as good as flipping a coin, while anyone paying him to do so will be believing that he can actually do something (otherwise they'll just flip the coin themselves and save the $50).
The "are you going to heaven" guy might actually, honest to god, believe in what he's saying = no scam. (Although if he was, he'd probably be more likely to be explaining how joining his religion will secure admittance to heaven)
Explain to me when you aren't doing that. You've basically described every consultant, lawyer and expert in existence with that statement.
All those other guys predict non-binary scenarios. If I try to predict the result of a dice-throw by throwing a dice myself, I'll get a success-rate of exactly 1/6, but when factoring in the number of outcome scenarios, I'm doing exactly as well as the coin-tosser.
With the 200% guarantee, that might not even be illegal.
EDIT: Finally got to read the actual article and realised that this is already covered. Sorry - /mea culpa./
In this case, if the prediction is wrong (not the best widget/customer not satisfied), they can get their money back.
Come to think of it, the prediction claim isn't much different from most test prep higher score guarantees.
If, on the other hand, you simply said "Pay me $50 and I'll guess if your baby is a boy or a girl" It wouldn't be a scam, nor would anyone pay for it.
To put it more simply, if the customer handing over money depends on them believing something that isn't true, it's a scam.
All you need to do is link the questions to something. As in:
How many brothers/sisters do you have? More brothers = +1 girl, and vice versa. There is no requirement to have any sort of science behind the reasoning of whether or not your +1 assertion is correct.
For me, having a history of never monetizing anything but my time, I can identify with a general sense of urgency. Still, I would probably never do something like this. But, if I did, I would certainly never tell anyone.
Edit: I changed my mind. I'll see you at the Kansas State Fair... look for the booth titled "Will your startup ever be profitable? Two questions will tell the answer. 'Free'"
