A few days ago, a video of a cellist was shared on facebook showing how he cleans/disinfects his cello in times of the corona virus:

 

He had his cello in front of him as if he were playing, a bottle of ethanol in his hand and a rag. He spilled alcohol from the bottle into the rag and rubbed his fretboard and neck with it.

 

I think that’s pretty risky, so I’ll write a few words about it:
The varnishes of the instruments are soluble in alcohol, all it takes is a splash to go wrong and you cause damage to the paintwork. Never tip a bottle of alcohol over an instrument!

Besides, instruments are not usually exchanged between people, so why should they be disinfected with alcohol?

To clean an instrument for the musician, I generally recommend only a fine microfiber or duster, one for the strings and one for the varnish, so that the rosin that was on the strings is not spread on the varnish. And wash both cloths regularly.

The rest of the cleaning should be left to the luthier. He/she is in the best position to assess how the respective dirt can be treated and which gentle agent can be used to clean it.