Not pretending to the absolute truth but from my limited experience with expired paper I avoid buying expired variable contrast papers. Fixed-grade papers (Ilfospeed, Brovira) hold up pretty well and are generally usable, variable grade is much worse.
Ilfospeed for example just goes a bit yellowish with the age, without fog. Which is much more acceptable for than Kodak Polymax of the same age which develops nasty uneven blotches. No fog, just develops unevenly no matter what. Agfa MCP goes just bad with even base fog.
Probably it has something to do with developing agents included in the emulsion.