mod. satisfactory; up to what is expected. (Colloquial. Snuff is related in some way to tobacco. Scratch may allude to the starting or finish line in a contest.) We felt that the entertainment was not up to scratch. The food was up to snuff, but the hotel staff was not at its usually efficient best.
Meets the standards. In the days of bare-knuckle fighting, bouts took place within a large circle drawn on the bare ground (that's where the phrase “boxing ring” came from). The contest began with the fighters facing off while standing on either side of a line scratched on the dirt in the middle of the ring. A fighter who was physically and mentally ready to take part stood at the line and was, therefore, up to scratch. “Up to snuff ” has much the same meaning. Powdered tobacco was said to sharpen the user's mind, so if you were up to snuff, you were mentally and also physically ready to go.