Hope that never happens to me. I sleep in my underwear. When someone comes to the door while I'm in bed, I grab the last thing I wore the night before to answer the door in.
I never knew that to be suspicious.
I think what I heard though was that she was in the clothes she wore the night before to a Christmas party. Maybe I'm not remembering that right. I do know one thing.....what I wear to a Christmas party the night before isn't exactly what I'd grab if something happened in the night or wee hours of the morning. I'd be more inclined to grab my sweats, or my robe, or even a pair of jeans and t-shirt.
I don't think it was what she was wearing that was a main cause for suspicion. I think it was only one small part of a few other things that created a huge ball of wax, so to speak.
Personally, I wasn't one to take a stand on who had killed JonBenet. Some people felt they just KNEW who was guilty, and that seemed kind of silly to me. Sure, we all talked about it and played the "detective" game, but no one but the killer knew for sure. So the rest of the folks were just screamin' at the wind, IMHO.