Some laserdiscs are read loudly by my laserdisc player. Why would this be? Is it just the way a disc may have been manufactured? Last night I watched Grumpy Old Men a laserdisc which was given to me for free when I picked up Elvira and the laserdisc player at times would read the disc loudly. This was a brand new laserdisc until I opened it. I can report my laserdisc of Grumpy Old Men does not have rot. I noticed on lddb that a lot of users reported rot on this laserdisc. I guess I got a good copy of it. I did notice a weird line down the center of the screen at times that would appear depending on the lightning in the movie. Keep in mind i'm watching this on a 65 inch tcl 4k monitor so it might she any weird issues the video may have but that's not rot.

Unusual.
I can hear a slight difference between CAV and CLV discs if i really tried in a quiet setting.

Is it more like a vibrating sound?

A loud vibrating sound and it tends to happen when I put movies on pause. However it seems like specific laserdiscs will be louder than other laserdiscs. Maybe it's coincidence but who knows or maybe it's the way my player sits on my folding table at times. Maybe I have the player on a certain way that causes the sound to be loud.

If it happens repeatedly with the same disc, it is probably slightly warped. If it is intermittent with the disc, it is probably something related to clamping.

In addition to what cplusplus says, take a look at the centering hole of the disc in question and see if they have any bump to them. I once had a disc that for some odd reason had excess plastic material in that area that made it impossible for my player to clamp it down properly so I kept having excess vibration in playback. I finally got fed up with it and gave it away to a friend.