Sylvia, Nope, can't tell old from new.
I go the lazy route for my succulent and semp soil. I buy cactus mix from the stores and don't amend it much. If anything I like to add large grain sand to it if I can find it. Sometimes this is referred to as architectural sand as opposed to contractor sand or playground sand which tends to be very fine. I do try to look at the mix before I buy. Some stores have/enable one to look at sample mix so that you can decide to buy or not. I don't buy the cactus mix that looks either too "potting soil" looking (appears to have no sand or rock or grit) nor do I like to see a lot of perlite in the soil mix.
Here's a photo of mix of use by EB Stone that I buy at the nursery. Photo shows the grittier make up of the mix as compared to regular potting soil. I also don't buy soil that has plant food already in it. I like to regulate my feeding times during the growing seasons.
I think different people with different zones and growing conditions will differ in what they like to use and what works for them. You should try and get info from someone growing succulents in your area/zone.
