Actually the word xenophobia comes from the Greek word "xenos", which means stranger, guest, or foreigner, so it wold do for "guestphobia" as well.

I think, as it crops up here, it isn't actually antagonism towards strangers at all normally, it's antagonism towards people who are identified as not being strangers, but as resident trolls in a fresh disguise, intent on stirring things up.

Myself, I think that kind of detective work comes a bit too close to witch-finding, and is only too liable to end up doing damage to people who don't deserve it. And when it involves people who actually are non-English speakers being brave enough to post on the Mudcat, that's something that really should be avoided. The best thing, surely, is to accept people at face value.

So what if you get taken in now and then? Chesterton once pointed out that people who worried too much about being "taken in" failed to appreciate that being taken in is the way to see the inside of places ad things.