Pantyhose and those knee high hose -- from back in the day when I used to wear them daily to work. Then, I started *testing* them . . .and discovered that if you hold onto this stuff long enough the elastic rots, gets stick, and crumbles! Great excuse to finally toss the stuff.
I have way too many pairs of socks. They never wear out. And then I started to buy tights, including ones in color. I should have skipped the orange and coral in favor of gold, since it turns out that gold is rather low contrast with my tan booties.
Toothpaste. And the stuff expires. If used when way too old, it tastes icky.
Makeup. Why can't I bring myself to dump the stuff I never wear?
Nail polish. I only started to use the stuff less than two years ago. Why do I have so many bottles? And why do I wear only the same four or so colors? And have a couple I've never even used. [But I think I'll open the black for Halloween and use the fiesta orange as an accent.]