What Scotty said about cutting the filters open after 1000's of miles of use is what I said the mom and pop auto parts store did, that resulted in them only carrying Wix now. The disintegration is troubling and was what they found in one of the K&N filters. This surprised me to be honest. The Fram filter media turning to a wet toilet paper consistancy happened to a member of our motorcycle forum pictures during the rebuild were provided. That wasn't an urban legend.
I would love to see some of these cut away filters myself after hearing about the status of the elements...Hmmm on second thought, maybe I would want to see. I aasume without cutting the filter you wouldn't be able to tell much. I've examined nearly every filter I've changed and have never seen an element looks odd. That includes nearly every big name filter out there.
One thing about the Amsoil filters is, unlike nearly ALL of the others, I don't recall ever hearing anything negative.