Yes it is the glue in some ways.
Boiling seems to reheat the glue and make it more transparent (that the pressing process failed to do) so the laser can read the info but I've done several tests on this and it seems myself and some friends only have trouble with the OXM discs if they have a Thomson drive.
After mine started giving trouble reading discs (starting with the OXM May '02 disc), I boiled a couple of them and it worked great. It wasn't 5 months after that, my Thomson drive died while I was in the middle of LIVE beta testing. My MS repaired Xbox has the Philips drive in it and it reads all my OXM discs even the ones that wouldn't work in the Thomson and were not boiled. So I blame the Thomson drive for all the problems with the OXM discs, because I haven't had a problem with any of the OXM discs since.
Xbox LIVE Gamertag: MAGGOT VOMIT
HT: Harman Kardon DVD50 DVD Player, AVR510 A/V Reciever.
Infinity Speakers: RS5 Towers, CC3 Center, BU2 Sub, RS3 Rears. Sony Bravia 52" W3000
"Please, no tears. It's a waste of good suffering!"