Absolutely!
Actually, if anyone is purchasing a wand, they will ALL be used, partially depleted wands. The only time a new wand with all 50 charges creeps into PC hands is if they make it themselves or if they have one commissioned to be made (costly!). As far as charges go, I have introduced a zero-level spell that allows a caster to roughly judge the number of charges in a wand or staff if the caster already knows what kind it is (spell reveals if the item has 20%, 40%, 60%, etc of its original charge).
Then again, I have a homebrew feat that allows a caster to create a wand with fewer than 50 charges (to save on cost) and another feat to recharge wands.