PPP will have egg on their face if Walker gets the 6, 7, 8 pt win that most non-Dem affiliated polls were calling for, as Krazen pointed out. And the closer the actual results come to We Ask America's poll results, the worse the sting for PPP.
For the record, I don't think Walker will win by 15 points. My prediction was 53-46%. And if Walker somehow does win by 15, the worst offender would have been Lake Research (49-49%), and not PPP.
I don't see how a 6 point Walker win would put any egg on PPP's face. They have him winning by 3. That's well within the margin of error for most polls. An 8 point Walker win would indicate an obviously less than stellar performance but it'd hardly be a disaster for them.
It would merely mean that they're a last place pollster.