Unbelievable

I own a Yamaha electric guitar made in 1985 lawsuit, SBG  model  as they were called ,Santana endorsed it ,Gibson wasn’t interested, Yamaha set out to prove they could make a great guitar,.The workmanship was incredible, where they fell short was the pic-ups ,Gibson had the sound. 

"There are many important factors which effect speaker sound including the outside enclosure. With that said I don't think Yamahas claim that the external finish improves signal to noise is too far fetched.

fedie, do you think that installing better pickups on the Yamaha guitar would be cost effective or are you better off with the purchase of the Gibson? I own a Gibson guitar.

Maybe the forgot the “comma” after the word  “finish”

All I know is that lacquer is important to piano manufacturers, as its use is correlated to the hammer stiffness/density and consequently the sound character we call brilliance. The lacquer/varnish used by Stradivari is the main reason why his violins can not be replicated.
How does it translate to the loudspeakers I have no idea. I remember though that piano lacquer and glue were mentioned in relation to the discontinued Bosendorfer speakers which were rather special.
It may depend on design. If Yamaha use the "sounding board" principle employed by that Bosendorfer, then the glossy lacquer will definitely affect the sound. If the cabinet is damped, then it does not matter whatsoever.