I'd say that rarity impacts the scores quite a bit, actually, but so do the qualities of the insect.I am getting swindled hardcore by Nat. I give him a Lantern Fly and a Raja Brooke Butterfly thinking that there's got to be some kind of base score for rarity, but LOL NOPE. The Lantern Fly didn't even score as much as some mantis I'd given him earlier in the day and the Raja B. was only worth 73 points. Is it even humanly possible to find something worth 80? I don't like that this "luster" stat is random; at least with size, I can refer to the encyclopedia to see if what I caught is near the record size.
My huge and awesomely colored tiger butterfly gave me a score lower than my mediocre Raja Brooke Butterfly that won me the contest.
But I agree that the second stat being impossible to predict is pretty annoying.