Okay, considering that about 40% of voters are of the "reuse" persuasion - yet are dramatically overwhelmed by the single-use voters - I'll bravely step forward and admit to reusing them.
My problem, however, is that no matter how neatly and systematically I fold 3 or 4 tissues into my pocket...after a day of walking around, the virgin ones look just as haggled as the one- and two-use ones that I've stuck back in there. So when it comes time to empty my pockets, I sometimes end up throwing away the whole batch just to be safe, rather than fish out an apparently never-used tissue, only to have to unfold it and discover that there's scant empty real estate left for my next deposit.
I've tried the "put the unused ones in the left pocket, and the used ones in the right", but then I'll invariably forget which is which.