I hate to say this but from all my experiences in the past one month, American students are the most difficult to work with. Least cooperative, most judgmental.
gk210: Well from what I have been able to gather, the class where I have the most interaction with Americans is a combined UG/Grad class and all the undergraduates taking it are seniors. Maybe its just the, dare I say it, high-hat attitude that comes with being a senior.