From CNN:

The microbiologist Philip Tierno doesn't feel comfortable staying in hotels. He knows too much. He travels with an impervious mattress and pillow cover to protect against the unseen debris that guests leave behind. When humans sleep they shed about 1.5 million cells an hour.

While the covers were developed for allergy sufferers, Tierno encourages everyone to use them at home and on the road.

And definitely ditch the bedspread, he advises. Hotel bedspreads became a hot topic when one featuring bodily fluids from several sources was introduced in boxer Mike Tyson's 1992 rape trial.

How hotels clean drinking glasses

An Atlanta TV station used hidden cameras to monitor how the drinking glasses in hotel rooms were cleaned. In one case, a housekeeper appeared to clean a toilet and the glasses wearing the same gloves. In multiple hotels, the glasses were rinsed in the sink and dried for the next guests, in violation of health codes.

The Health Magazine lists the 12 germiest places in America or the so called "dirty dozen":