Laserdiscs may be affected by the so-called laser rot. This is damage caused by chemical decomposition processes within the disc. The plastic casing consists of 2 parts that were bonded and "corrode" if poorly manufactured.
Not all laserdiscs are affected, usually only certain manufacturing locations. In most cases affected discs play without any problem, but have more or less bad image and sound quality issues. On some discs laser rot is visible as red or black spots and these discs would not be offered for sale, or only if the picture and sound are still okay and only with the appropriate identification in the product description.
Please note that we are not able to check the LaserDiscs due to the sheer amount we receive and have in stock. Every disc would need to be checked from start to end.
Sealed discs can of course also be affected, but can not be tested.