I find that it's good to listen to that top 40 stuff once in a while, just to make you realize how awesome jazz really is. I must admit to liking some of today's pop, but there's no way I have a passion for it. I agree with the poster who said he likes to hear a good variety of improvised music; that tends to help keep things fresh in that you're not really knowing what kind of nuances you might hear, because going from say Braxton to Sonny Stitt is quite a leap. Both play reed instruments, sure, and both were/are masters in their own right, but each can be appreciated on different terms. I wouldn't rate one as being "better" than the other; I dig both of them for different reasons.
Or if mixing it up doesn't work, give it a rest for a while, as Chris mentions. That also works wonders, because when you come back to listening again it seems like a breath of fresh air (for me at least).