I always bring my own pillow and blanket when I go on a trip, but it has little to do with fear of germs. The problem is, as a person who is serverely allergic to dogs and cats, I have a very hard time finding hotels that don't allow pets. I'm always worried that people had their pets on the beds and vacation is the last place I want to end up asthmatic and on prednisone! So the bedspreads come off and my blanket goes on. That doesn't always solve the problem, but it helps not sleeping immediately next to animal fur. It seems extreme to bring bedding from home, I know, but it's the only way to handle the problem, since the hotel people lie like rugs about how clean their rooms are. I always ask when checking in (assumuing they allow pets) if they change the comforters after a pet visits. They ALWAYS say they do, but after reading this thread, I'm in even more doubt than ever before.
I wish hotels would have animal rooms and non-animal rooms much like there are smoking and non-smoking rooms. That would save their allergic visitors a great deal of hassle. One in ten people have my problem, yet it is nearly impossible to find hotels that don't allow pets.