[morzh]

Well, for heat destroying paint I can tell that I painted the ballast tube from Stromberg Carlson after I removed the rust by naval jelly.

However. I used the enamel I got with my gas range for taking care of nicks and chips of the cooktop panel (right now it is in a condition that makes any nick look anemic - I cook a lot and do not necessarily wipe right away, so the enamel goes to other uses).
It stands well to heat, but then it was designed for this exact purpose.

Now as for black color, a material that is black radiates better, hence anodizing heatsinks and such, but then anodization does not detract from heat conductivity serving as heat insulator, which paint might do.

This said, I have an impression our friend here read somewhere various things about improvements, such as sequencing voltages and painting shields. I even think there may be websites with people who might believe those are all great things to do.
To me these theories hold as much truth as the theories of Monster Cables which for the price of $200 - $1000 a set will greatly improve your sound. I am sure they will. I will let other people test those theories though.