I received a bunch of old paper; quite a few packages of varying mfg, types, grades. They were all from a single source so I suspect (but am not sure) they were stored at least somewhat the same. The packages were not dated but based on packaging, I could get a sense of relative age.
I found great variation of the degree of fog and not always consistent with the apparent age of the paper (based on packaging). I don't have my notes handy, but I believe that some brands/types seemed better than others when it came to fogging.