Take a pic...some of what you describe us no big deal (for example the yellowing)...the other parts of the description Are hard to determine exactly what's wrong. Also, how pressure dented is the deck?
yeah sorry i didn't think to take one while i was down there. but i looked at the carbon fiber on another futureflex board and it looked just as weird, i guess the discoloration and separation on the rails is normal? but it's not pressure dented too bad, just about the same as your average used board. and the dark spot doesn't even look like water damage, idk what it is to be honest. it looks kinda like someone used a pen to draw squiggly lines in a little 5 inch x 5 inch space, except it's right under the glass. other than that i think the cheap price is due to an ugly traction pad replacement, and the shop employees not knowing how much it could be worth (assuming it's ridable).