I use them all the time around my house cos they're warm and comfy, but i wouldnt really use them as pants unless it's over a really long shirt or a short dress.
I prefer tights to leggings cos leggings are see-through, and i prefer not to let others see my ass or my undies
If a supermodel wears them, they look good. However, trash bags and unconventional food-dresses also look good on supermodels. Personally, I don't have the balls (word choice fail) to wear them, but I try to avoid feeling female when at all possible, so I don't count. My opinion probably doesn't count, either, but I'm opinionated like that, so I'll say it anyway. I don't necessarily like them, since they are often reminiscent of sausage skin, and I certainly wouldn't be caught dead wearing them (as much as I enjoy comfortable clothing), but I wouldn't stop anyone from wearing them.