I look down upon someone in pajama pants, any hour. I do not look down upon sweat pants the same way, because there are a number of reasons why someone might be stopping by the store in sweatpants. There is one reason, and one reason only, for going to the store in pajamas. You were too fucking lazy to change.
Furthermore, the preponderance of chicks that wear pajamas to the store ALSO insist upon wearing their fluffy slippers as well. Which is a whole other level of disgust for me.
The only exception to this is if I'm in a college town, near the college dorms/apartments, and a gaggle of giggling girls are all in their pajamas and fuzzy slippers. That's either an event, or I'm just more tolerant of hot sorority chicks, which I freely admit.
There is zero reason a male over the age of 14 should ever be in public in his pajamas unless he's dying. Or possibly trying to get pussy, but I would have to see the specifics to allow that.