Very very rarely will I leave the house looking a mess in sweats, but sometimes there are days that I have college and just can't bring myself to dress nicely. Sometimes its sweats, sometimes leggings. All I know is those days I NEED comfort.
I rarely go out in sweats. Only if it's the middle of the night and I'm running to the grocery store for one item. I will occasionally go out in yoga pants, but I usually take the 10 seconds to throw on some jeans.