tlorber,
Yes, bad valve guides could cause blue smoke, typically not at a idle, but usually after accelerating following a closed throttle, high vacuum condition. The classic example is the car or truck cruising down the long, steep hill on compression. When it reaches the bottom of the hill the driver gives it some gas and out pours the blue smoke.
Unless one guide suffered a failure, all intake guides would wear with accumulated engine mileage.
Stuart
