Does remote control degrade the sound of tube preamps?

It would not surprise me if it remotes do alter the sound. But IMO the convenience outweighs the tiny fraction which it may cause. I might think different at 35 yrs old. But at 71, I won't buy a preamp without remote. Besides that is that Conrad Johnson does not make a preamp which comes without remote. And they are among the best  top tier preamps. Whatever the case, I don't care

it depends

in general it probably depends more on the volume pot configuration, not so much the remote control of it

Unless the remote circuitry can be removed for comparison we will never know.  Meanwhile just listen and decide if it sounds good, Remote or no remote.  Now what other impractical issues can we all worry about?

Great question.

For decades, meters or displays would be included in high end equipment, with the ability to defeat them. In the last few years Audio Research took the problem head on. They decided, if they were to have “silent” meters they would have to design and manufacture their own… ones that did not impact the sound (ghost meters). Before this audio companies just purchased generic meters… and they interfered with the sound quality.

This is how the high end moves forward. As a manufacturer you can choose the cheapest parts to make a piece of gear (this is how we got $20 Blu-ray players), or chose the very best component for a given design. Then, when it counts… make your own… think Focal… making their own drivers.

In theory anything you put in the signal path will alter the sound (usually negatively)

https://tortugaaudio.com/docs/ldr-volume-control2/

Turtaga Audio makes an optical based attenuator that doesn't effect the signal path.

or

The Hornehoppe 

The Truth passive preamp. 

http://www.thehornshoppe.com/the_truth_pre_amp.html