I bought this helmet in America in the mid-90's.I used it for maybe 1-2 years (as well as another helmet).I really looked after it. It was always kept in a cloth bag when not in use. I don't remember ever dropping it. It has been in my loft all packed up safely for 20+ years.
I've had a good look over it and can only see very minor cosmetic damage. 
Size is shown as 6 7/8.
I've tried to photograph them:
There is a small blemish at the top/middle of the visor.
There are 2 very small chips to the rear. 
This helmet would no longer be within regulations to wear as a safety helmet.
It would make a fantastic display item or an airbrush art project.