I guess the insult, from Rand, was that the VUX were ugly. However, the VUX reveal later that there is another reason (a deeper reason) why they don't like humans:
I quote:
But now you have forced us to reveal our REAL reason for hating you humans an embarrassing reason with no acceptable justification, but nonetheless undeniable! Human! You are SOOO ugly, SOOO hideous to us that we will NEVER be able to find peace with your species! Whenever we see your kind, we just want to kick you!... stomp on you!... squish you!... ...vaporize your ugly faces from the entire universe! We know its unreasonable! We know that you had no choice about how you look! We know that it is cruel fate that the Creator made you appear like putrid excretion but WE JUST CAN'T HANDLE IT! Why right now, because of your insufferable wretchedness I am faced with a grotesque choice: keep talking to you and regurgitate uncontrollably or break off communication and attack your vessel...
I guess the insult, from Rand, was that the VUX were ugly. However, the VUX reveal later that there is another reason (a deeper reason) why they don't like humans:
I quote:
But now you have forced us to reveal our REAL reason for hating you humans an embarrassing reason with no acceptable justification, but nonetheless undeniable! Human! You are SOOO ugly, SOOO hideous to us that we will NEVER be able to find peace with your species! Whenever we see your kind, we just want to kick you!... stomp on you!... squish you!... ...vaporize your ugly faces from the entire universe! We know its unreasonable! We know that you had no choice about how you look! We know that it is cruel fate that the Creator made you appear like putrid excretion but WE JUST CAN'T HANDLE IT! Why right now, because of your insufferable wretchedness I am faced with a grotesque choice: keep talking to you and regurgitate uncontrollably or break off communication and attack your vessel...
end quote
Thats SC3 fluff tho. Because SC3 was made by different people and chucked out a lot of the SC2 ideas and storylines, things like that (especially such a cop-out thing) are not considered cannon by some.
As Xander just pointed out, that quote was pulled from the UQM (SC2) content files. I remembered stumbling across it once, when during a long game, I tried to be-friend the VUX.... Waste of time, but I got a LOT of RUs out of it.
It is what Earth Xenobiologists call them, and thus why name V.U.X. -> VUX. (Sc1 manual)
Now, I'm not an expert on these kinds of things, but aren't biologists (xeno or otherwise) supposed to be scientific? I hardly think categorising a life form as "ugly" counts as scientific...
Personally I think the Umgah look worse than the VUX... Same with the Ilwrath. But that's just a personal thing of not liking blobs with eyes and mouths all over, nor liking spiders.
However, I agree that it doesn't sound scientific. Maybe all the good scientists were at Unzervault?