Certain characters? You mean her lover and party leader? I can buy Haley not knowing which nether region Sabine came from, but Nale? Not buying that.
It is pretty well documented that her origins are a running joke, just as the plentiful references to Z as either male or female have yet to resolve that conundrum.
I'll be happy to await the following comic to see if Sabine saves vs. the banishment. When it comes to story, even a 1% chance which occurs can be just a part of the plot.