Sally can come off as a bit of a snob, and it's understandable that people may dislike her for that, but you also have to remember that she's a kid. She probably wasn't taught right from wrong in the orphanage, and thus doesn't behave the same way Monique does.
Not to mention that the aliens speak "Gwanian" and can't understand English*, so it makes sense that they don't really understand Sally as much as we want them to.
*For those of you who didn't see earlier threads of this series, the reason the humans in Planet Gwan (and us viewers) can understand what the aliens are saying is because of their Black Matter Collars. The aliens, however, are clueless to this. See this episode:
