My point is that you can never be 100% certain you have a homozygous spider. Even if one where to produce 30 spiders and no normals bred to normals there would still be a 1 in a billion (actually 1,073,741,824) that it was just good luck. Just like you can never prove 100% that a homozygous spider isn't possible. Even if the first 30 potential homozygous spiders all failed to prove there would still be an about 1 in 191,751 chance that it was just bad luck that all those 33% chance homozygous spiders turned out to just be hets. Of course there would also be the chance that the selection of possible homozygous wasn't random (maybe homozygous ones look or act a little different or for some reason weren’t as likely to be the first ones bred by the public).

So, if you can't be 100% certain, when do you decide enough is enough? I think if there was only a 1 in 1 billion chance of being wrong most of us would consider it proven. Would anyone really feel they need better odds than that JUST to be sure?