I've e-mailed customer support in the past, and it's been told to me that King.com will send you a 1099 form by the end of the year if your winnings exceed $600. My winnings exceed well over that, and I haven't been asked for my taxpayer ID/SS yet. Odd...
Paypal does not report your ledger to the IRS -- however, the IRS *CAN* request Paypal to turn over your records if they deem it necessary (you somehow triggering an audit, inconsistent numbers with your bank deposits, etc).
IMO, play it clean and report your earnings to the IRS. You won't have to pay a huge percentage of taxes on your winnings, and if you're slick enough you can get away with certain deductions (utility, computer equipment, entry fees, etc). I was thinking about dodging taxes too, even on a freelance thing I do where the company will not be sending me a 1099...but if the IRS knocks on your door, it's just not worth it. Be honest!
Jacob, aka Meikyousisui on King.com & Worldwinner.com