I wouldn't say anything, but I'd feel pretty gross. but that's just me, I have to shower when I get up and get a fresh change of clothes otherwise I feel dirty even if I'm not. xD

I have stayed over at somebodies and then had to wear the same clothes until I got home in the morning, but I don't sleep in my clothes (i just cant!), I'll borrow an oversized t-shirt or something to sleep in.