An alias is just that. It means nothing. I have Japanese in my alias. I buy stuff from people in Malaysia who have names of UK pop stars in their aliases. It means zip.
You do know that USA is full of immigrants right? You do know that many US citizens don't even speak English or very poorly?
You do know that there are many people there with permanent residence or on work / study visas and they sell on Ebay? It's also more likely that new comers who can't get work elsewhere or students will supplement their income on Ebay by selling stuff.
www.census.gov/prod/2010pubs/acs-12.pdf
55 million people in the US speak a second language, which may even be their native language.
24.5 million people in the US self report not speaking English very well.
You do know that EBAY is an international place? You do know that only a minority of the world's population speaks English?
Ireland:
It has many immigrants too. And there are native languages too.
You seem prejudiced against non-native English speakers. A person's ability to speak proper Queen's English or employ grammar does not correlate with their honesty. Unless you have proof of this, you should acknowledge this and know you erred.