Rubbing alcohol is OK - but the yellow, regular formula "Listerene" mouthwash ( regular or store brand ) cleans that crud away LOTS faster.
Back in the old glass-tit CRT days, I used Listerene to clean computer monitors. No streaks, plainly superior to actual glass-cleaning products. - Cheaper too, needless to say!
It is also superior for removing accumulated dead skin and grime ( scum-grip ) on the steering wheel and arm rests in an old car or truck.
I wouldn't use it on a guitar fingerboard as the alcohol in it would tend to dry out the wood - but I would not hesitate to use it on the body of the guitar.
They end up with scum-grip on them, just like an old car's steering wheel.
I have used it to restore a few old Kenwoods and recommend it highly.
As with all clean-up stuff, test it on an area that is invisible or hard to see before you start using it on the front panel and its lettering - to be sure that its ingredients are compatible with your particular radio's finish.
73 DE Charles, N5PVL
The "S" word... It's not the socialism, it's the stupidity behind it.