Over use of hygiene causes rapid evolution bacteria. Disinfectants should only be used for high risk situations. Like after contact with animals that are known to carry diseases and to clean up a counter after contact with raw meat. When you use anti bacterial products you kill all but the strongest bacteria then that bacteria reproduces and bacteria reproduces quickly, then the next thing you touch will likely cave as much bacteria and in no time you will have the same amount of bacteria as before. We shouldn't avoid minor illnesses it is a simple fact of life and you're immune system will be stronger after more prepared for similar illnesses.
I do not think that Americans are too obsessed with hygiene. Procedures such as washing of one's hands and use of bacterial wipes are important hygiene techniques as this helps prevent the spread of disease. Other hygiene practices such as brushing teeth serve as preventative to adverse health affects such as cavities.
I think, when it comes to hygiene, American's may have one of the toughest standards when it comes to hygiene, but I do not think that is indicative of Americans being obsessed with hygiene. I believe our habits are probably on par with other countries like the United Kingdom, France, and Austrailia.