They can't give a bad rating, their clients are charged way to much for the rating. Ask any past JD Powers client why they are not currently rated and they will complain about the money that they charge.
JD is just a little basis but, it a decent guide-Consumer Reports is a good guide on consumer ratings on wood windows, there are too many vinyl windows to even rate. I would have to argue why Pella gets the top rating every year it seems there is some back door dealings with JD-
My ratings on most common wood windows:
Hurd before bank rupt
Vinyl windows most common MFGs
All Side high grade
Silver line Upper Grade
Jeld Wen Vinyl
Pella threma Star
Emily: I am doing a survey for a research company on Pella, would like to talk to you since all the ones I have spoken to so far are pro Pella, it would be good to speak to someone who is not as well. Could you contact me please.