That can pretty much be said about any poll. Quin hasn't seen wild swings like WaPo and Rasmussen... it's been in the 3-9 - point range the whole time.
Polling is an inexact science at best, and it’s hard to know who to trust. That said, Quinnipiac and Public Policy Polling are two of the least trustworthy, as their liberal biases skew their samples and are generally used to create the result rather than measure it.
Rasmussen is generally the most reliable, but in the end, it all comes down to who has the most accurate likely voter model, and no one knows that until after the election.