I'm surprised that no one's mentioned yet that some exposure to germs is GOOD for you. Constantly washing your hands is an excellent way to make sure that when you are exposed to something bad, your body will not have built up much resistance. The more bugs you're exposed to, the stronger your immune system is.
I personally pay minimal attention to such matters, mostly out of societal conventions, and also make sure to avoid anti-bacterial products. I believe this is a major reason why I rarely ever get sick. I never get a flu vaccination, and haven't had the flu in over 20 years, and when I catch a cold, it usually lasts hours with the worst symptom being a sore throat. I honestly can't remember the last time I got truly sick.