Corrected entry: At the beginning of the movie when Stitch escapes to Earth, the Grand councilwoman is having him tracked and begins to ask questions about the planet, as well as requesting an expert about the planet as she has apparently never heard of it before. Near the end of the movie, in the scene where Stitch has been captured and being taken to the Grand Councilwoman's ship, the Grand Councilwoman comments that Mr. Bubbles "looks familiar", to which he responds that they had met in Roswell. This implies that the Grand Councilwoman had in fact been to Earth before and would have known the answers to the questions she had about Earth earlier in the movie.
Phixius
30th Sep 2013
Correction: Having been to a place does not mean you know anything at all about it, and it certainly does not make you an expert on the subject. There was supposedly an alien crash landing at Roswell, indicating the councilwoman's stop on this planet was unplanned and unintended. She stuck around, in seclusion, only long enough to catch another ship off to her original destination.
Phixius ★