Scart cables are made up of 21 smaller cables. Signals can leak from one to another resulting in odd effects, such as colour bleeding and pulsing, and even a ghost image of another channel in the background of the picture of the screen. Scart cables with individual screens on each wire help prevent this. This type of scart design is more important than the colour of the plugs - like the other post said, regardless of the hype over "gold scarts", gold on silver is not the best mix. Gold on Gold is best, then silver on silver.
By the way, what do you do if the equipment on one end the cable has a silver scart sockeet, while the equipment at the other end as a gold connection? Can you buy a scart cable with a gold plug at one end and a silver one at the other?
Dave