How about they are not? Radical I know, but what about having a button on the bottom of the page where you could click to say "this was a good article, flattr it"?

Now you might say very few people would pay for it, but if we assume something like flattr, then your money is already spent. All we are talking about is who gets the booty. And if you aren't a flattr user, then you just get an excert and a signup button.

That version kills click-bait, because who really likes those kinds of articles?