Since laserdisc is an analog format like vinyl, there's no such thing as 'bit rot' with them the way there is with other forms of digital media.

The problem laserdiscs can suffer from is called 'laser rot', though this has nothing to do with the laser rotting the medium, and everything to do with how they're stored by the end user, and how they were manufactured initially. Laser rot is a problem endemic to some discs, and virtually unseen on others, where imperfections in the mastering process result in the destruction of the metallic later that holds the video information.

Minor rot shows up as minor glitches (brief flashes of white in one particular area of the picture, skipped frames, and audio problems). Since laserdiscs are analog, however, the player will just keep on playing despite the damage, while a DVD damaged in a similar fashion will attempt error correction but it can freeze if the disc is too unreadable. Films are still watchable in this state.

Major rot, on the other hand, will completely destroy the utility of a disc, with large-scale frame drops and skips, missing audio information, and massive video degradation to the point of unwatchability. Rot resulting from a manufacturing defect is nearly unavoidable: if a given disc was pressed at a certain time at a certain plant, it's almost guaranteed to develop the problem. Early laserdiscs were first pressed in the US at a plant set up in an old furniture manufacturing facility, which was not cleaned and sterilized prior to equipment installation. As a result, nearly every disc that left that facility either shipped in a defective state, or developed one soon after. These discs are nearly impossible to find in anything approaching a playable state today.

This is a quick 1.5 minute long example of what minor, serious, and severe rot does to a disc. :)