"The 83's are plastic,... 58's are rubber..."
I think they are all made of the same material, but, from what I have read, it seems that those 83 boots were made with big bellows for a lot of extension and small compacted length. That makes them more prone to making a mess. That still doesn't excuse them for messing them up, though. I may go with the 70 series or something else that is more like the 58 series but a little shorter.
http://www.daystarmx.com/productdetail.php?productID=939"Yours aren't defective,.. they are just a different animal..."
So, if I pinch the bellows and go along the circumference, and find that the material is thin on one side and thick on the other, as well as
visibly imperfect in shape, I should accept that as normal for vinyl boots, huh (as opposed to rubber boots, which are supposed to be perfect).
Seems like you don't expect much from vinyl, do you, Bot? Well, I do. Think about it-- Does your explanation really make sense?
Do you want me to take a picture of them?