Hi Joey-
I wouldn't think hotel linen would be a problem. I would certainly hope they do their laundry in a similar fashion to what hospitals do, too many germs and nasties to pass on there.
I've found that when my Joe has some little pimples that bleed or larger areas after minor surgery, or minor injuries, for example, blood is one of the hardest things to get out. If you have white sheets, you can always bleach them, but with colors, it's a BIG problem. Peroxide helps a little, but doesn't get it all out, and even the special laundry items don't work. Maybe you could bring your own pillow and sheets when visiting friends, if you're prone to nosebleeds. It could also bleed through onto the matress.
I don't have a good answer to the friends situation.