Some studies offer surprising, even stunning conclusions.

This isn't one of them: Public restrooms are every bit as filthy as you would have guessed... and maybe even worse.

A microscopic look at a dozen public bathrooms on the University of Colorado's Boulder campus found 19 types of bacteria running free -- including stomach bacteria on the door handles.

That's a sure sign of something you've probably always suspected: Plenty of people don't wash their hands when they're done... and grab those door handles with their filthy paws.

And that means you can have the most careful habits in the world and wash up after using the toilet -- but end up with filthy, germy hands anyway when you grab the doorknob to leave.

On the other hand, women seem at least a little cleaner than men (again, no surprise), since the researchers found more of the bacteria associated with urine on the soap dispensers.

While that means women are going from the toilet to the sink instead of the door, it means you've got to watch out for soap dispensers as well as door handles now. And while we're at it, you can add one more to the list: toilet handles.

People don't just flush with germy toilet hands -- they also use their feet, as researchers say the soil bacteria usually found on shoes turned up on the handles.

That raises an interesting dilemma: Do you refuse to compound the problem by using your hand and risk picking up that dirt bacteria... or make it worse by using you own shoes?

As bad as all that is, the public restrooms near you might be even worse -- because the campus bathrooms used in the study are cleaned regularly. I'm sure you can think of a few examples of bathrooms that get much less attention.

I'm talking to you, I-95 rest stops.

On the other (clean) hand, bacteria alone isn't something to panic over. It's gross to think about, but you're exposed to potentially harmful critters all the time. A healthy immune system will fight them off and you'll never even know they were there.

And don't forget to wash your hands.

P.S. Bathrooms aren't the only common places you'll find nasty germs. One study last year found they could be hanging out on your computer keyboard, while another study found that they could be lurking on your cellphone. Sometimes, it seems like you can't touch anything.