I (and two others) got a TV advert for one of these penny-auction scams stopped quite quickly. Or maybe they didn't have enough money for more than one advert

Just because it's a scam, doesn't mean they actually make a lot of money from it.
(What was a bit upsetting was that it was stopped more about a formality, not about the fact that it is actually a scam. When you "win an auction", you have to pay the auction price, but you already paid for your bids, so the cost for the "winner" is higher than they actually advertised; that's why they stopped the advert. The fact that all the losers lost the money they paid for bids, which is the real scam, wasn't mentioned. But maybe if they have to give more details in an advert, the scam becomes apparent to more people).