To spend your poker points, talk to a brush at the desk. Then
make sure when you spend them that they take the comp from the poker room.
Last Saturday I got in a little late in the day and parked with the valet, played a mediocre session, played a little video poker for ~10 minutes, decided to use some of my many poker points at the buffet, played another session (on a much better table!), and then when I went to get my car and go home at 10pm, the lady at the window tells me, oh, you just missed the cut off, that'll be $49, oh sorry, sir, you don't have any comp points.
Turns out because of the video poker that I had just crossed the threshold to having 20.09 points in my "real" comps, and the buffet took 20 of them instead of the poker comp, and so I had no points left to pay for the valet! Somehow when I had less than 20 points the last six times, that was never an issue.
So it took me 40 minutes of running around, first to a Red Desk who couldn't really help me beyond giving me 1 free comp dollar so I could get my car out of hock, then to the brush desk to ensure that they didn't screw up providing the comp in the first place (nope, the brush it all did fine), and then finally back to the buffet to talk to the manager who, it turned out, was the only person in the whole casino who could get my accounts back in order (although even she had to phone a higher up).
It was a real PITA! If I hadn't used the valet -- and I usually don't -- I wouldn't have known except for some fine print on the buffet receipt, which it never would have occurred to me to check, and I still don't really know what I'm supposed to look for!