can foreigners auditions for x factor usa 2013 if you are from another country?, kind of a yes and no, answer to this question.
it says on the x factor auditions website for 2012 rules this:
"Each and every member of the Act is a legal U.S. citizens or permanent U.S. resident
who is eligible to work full-time in the United States;"
so that is some of the rules there, if you can meet those requirements then you could apply to the x factor usa.
also if you are under 18 years of age, you have to be accompanied by a parent/legal guardian who will register you at the auditions as well, so that is some of the basics there, and so it is down to meeting the correct requirements to auditions which is probably difficult if you do not live in the usa, you would probably need a usa visa and the right to work and live in the usa and some where to stay and support yourself, so it is probably not easy to audition for the x factor usa if you are not a usa citizen really.