Ralph-
Sorry I didn't see this post earlier. I've been in this business for nearly ten years- I won't go into brands. If your liner was near new in April(?) (your first post about this), then the rhino rep gave you bad info and charged you more with the shine. All polyurethane and polyurea liners including rhino and mine will oxidize, but will not smear black crap on you. You would wind up with more of a chalky grey "grit" on you, but it would take a year MINIMUM to get to this point. If you ever wash your truck bed out, you can probably extend that time out to several years.
The only thing that causes what you describe is an improper mix during the spray process. It definitely sounds like a bad mix.
I'd start by getting my money back on the shine junk, and then make them adress the real problem. If it is as I suspect- be aware that there is no "fix" for the problem. Do not allow to try to fix the liner that is there. It must be removed and a new liner installed. You will need to give up your truck for at least a day or two, as removal is a real tough job, and the guys will not be the least bit happy. If they are a reputable shop, they will take of you, although they will be cursing the heck out of you when your backs turned <img src="/forums/images/graemlins/smile.gif" alt="" />
Sorry for you troubles, let me know if you need any more info!