Toner does degrade over time ... it picks up moisture, and loses its fine powderiness, forming larger,
hard grains. Subsequently, parts of the cartridge or even the printer may take damage. Besides, the
photoelectric drum loses its electrostatic chargeability over time (not in those new technology printers
that have a permanent lasts-a-lifetime drum). As a rule of thumb, you should use up one cartridge
every three months or so to avoid either problem.
What you want is a low end inkjet with disposable print heads - so if the jets dry up, you can take
the head out and let it soak for some time on a wet paper towel, and if that doesn't help use a
new one.
Low-end Canon and most HP printers have that, Epson and most Canons use permanent heads.
Lexmark rule themselves out by the ridiculous cost of cartridges, IMO.
regards, Peter