Actually, the fact that they have been around for a while makes the probability that there IS quite a few homozygous spiders out there, unless it is homozygous lethal, but since I have seen nothing other than speculation on that point, I'm inclined to believe it is not lethal.
I think what you meant is that the homozygous form is probably not visually different from the heterozygous form, and yes, no one is expecting a visually different homo form to turn up. If it had one, it would have been seen by now.