Shutter count alone might be used to guage the remaining lifespan of the camera, bundled with the actual camera age, it can tell you how old the electronics really are. Cameras that are a few years old with a low shutter count is relatively ok, if the cam has been stored in a cool drybox. If its many years old, and has a high shutter count, it means the previous owner has used it alot. This means the electronics are probably more worn out and hence the camera has a greater chance of breaking down anytime soon. Our high ambient temperatures, especially when the camera has been used alot outdoors, tend to destroy electronics faster than cooler temperate climates. Even if the circuit boards are fine, the sensor may have degraded in its performance. (ie less saturated colour, increased noise etc) Replacing the shutter is then very cheap compared to replacing the sensor.
Again, I must warn that such values are very relative and cannot be used as an absolute guage. Some cameras break down right out of the box, some break down after 3 rated shutter lifespans. Some cameras have their sensors go all crazy after a few years, some loose its day 1 qualities very very slowly.