As a child, my family celebrated each Christmas by hanging plastic-wrapped candy canes on the tree. We used the same candy canes each year, yet they always looked just as delicious as the year before. So the question is, "Can candy canes go bad?"
Of course. But let's elaborate.
Candy canes have a very distant expiration date, mainly because they have a very low moisture content. Sugar (much like honey), when in its pure form and stored under the right conditions, is not known to have an expiration date. The higher the sugar content in a piece of candy, the better its shelf life will be. If the candy cane in question is almost pure sugar, it can last a long time. However, most candy canes these days are composed primarily of high-fructose corn syrup.
Secondly, a candy cane's expiration date depends upon its packaging. Hermetically-sealed and vacuumed-wrapped packaging is generally the best, followed by sealed foil-lined plastic, then wrapped foil and finally wrapped plastic or wax paper. Anything unwrapped or loosely wrapped will spoil much more quickly, due to exposure to the air.
Finally, candy cane expiration dates depend upon the storage conditions. Is the candy exposed to direct sunlight? Is it in a warm and humid environment? Is it collecting dust and within reach of pests? Is it moved frequently and in danger of becoming physically damaged (punctured, ripped, etc.) or experiencing sudden changes in temperature? Any of these atmospheric factors can dramatically shorten any candy cane's life expectancy.
In short, candy canes DO expire. However, a very hard candy cane made of pure (or nearly pure; we can allow for some food coloring) sugar, shrink-wrapped in vacuum-sealed foil-lined plastic and stored in a cool, dry, dark place is likely to last forever (until you eat it, of course!).