You should work towards getting an additional discount based on the condition of the "new" truck and then take it somewhere on your own to be detailed. I can't say every dealer detail shop sucks, but im betting its in the high 80-90% range that just do the bare minimum. They typically hire unskilled kids that work for cheap and do not care about doing a good job.
I learned a huge lesson and got very lucky when I bought my truck last year. Bought a truck, signed the papers on a Friday evening, but it had been sitting in a satellite lot somewhere and was pretty filthy. They practically begged me to take it over the weekend and just bring it back to get cleaned up later. They told me how awesome their detail shop was and how it would be better than perfect, blah blah blah. I told them no way, paid a deposit on my credit card and I would be back Monday to pick it up.
I come to get it on Monday, it had tons of swirl marks, some significant scratches, tree sap residue, residual grass/brush stuck under the bumpers, etc, etc. They took it back to their detail shop where there was a kid ( looked 18 if he was a day) that basically told the manager it was a busy day and they did the best they could do.
Luckily, I never took delivery so the contract was not complete. I backed out, they eventually told me they would refund my deposit but they never did so I eventually had to contest it with my credit card company and got 100% refunded. Had I have drove the truck off the lot or paid a cash deposit, I would have been totally stuck.
Went to another dealer and was able to buy a truck that was literally just getting unloaded from the transport trailer and had not been sitting around for months. Got a better deal, more for my trade and the truck was pristine.
Sometimes you get lucky and things work out. If you havent taken delivery you should be in the driver's seat regarding how they handle the issue. If you have already taken delivery you are likely at their mercy and will have to either work with them or take it somewhere on your own and pay out of pocket.
Good luck!