Should be noted that this poll was conducted on behalf of the VEA, which endorsed Northam.
I would hope they wouldn't fraudulently change 24% of voters in Northam's benefit.
PPP wouldn't manipulate its results like that, but it's good to know who's paying for these numbers.
But it's similar logic to any other internal: The group that pays for the poll decides if it becomes public or not, and they won't make it public if it shows a bad result for their candidate. So even if it's a well done poll, who's to say that they didn't have some other pollster poll the race last week, and they chose to release this one rather than the other one because this one has a more Northam-friendly sample?
Selective release is separate from direct manipulation of data. Both may be used to get a beneficial result, but one includes legitimate polling while the other is fraudulent. It's a good reason to be wary with internals, but given a credible polling org it should still be a result within reasonable bounds.
