Why is it that immigrants are so filthy towards americans?

just yesterday i over heard a mexican/india guy call an employee that works for him and i quote "typical american slut" then when i confronted him on that he started calling me an "american ******, and american piece of ****" why is it that they come to OUR country and then talk **** to us? it was there choice to move here in the first place, and if they wanna be racist towards us. then why do they move here, because of them is why america is at a economical downfall.cause we have to increase our border patrol so they wont try to sneek over here to bad mouth us, also they get the jobs because they can get paid less money then the people who actually live in america legally. If anyone is in the Reno area do NOT go to Atlantis casino and resort, there managers are very rude towards there employees and customers.