I do think the NBA had (and might still have) a huge problem because a ref can make a huge difference in a game. As far as the NFL, I just don't see it. Maybe there have been bad calls but if there were truly a fix in, would they risk the game getting to the point of needing a miracle play (that they can legitimately overturn without it being obvious there was a fix?)
The argument about Nielson ratings was comical by the way. Even they mentioned the Jets are #18. The Knicks were horrible for a decade and they're in the NY market. I do think there are cases where cheating might occur (e.g. Ronnie Harmon's 4 fumbles in a bowl game against I think UCLA years ago) but I think that's the exception.