I'm just gonna jump right into the rustle here for fun: While I am most likely too great of a fool for such a test, I'm certain Sherlock himself would agree that he would not be the best fellow. His mind is specialized for solving crime, not for subterfuge (outside his use of disguises and assisting parties), and chances are not for most of the subject that the test will deal with.

He has a mind palace/photographic memory, so memorizing everything on the test won't be a problem for him. Plus, knowing Sherlock, he'd probably give the guy ordered to make sure you don't cheat laxatives in his cereal, and then replace him as a substitute lol But in all seriousness, I agree that he might not be the absolute best, but hey, I think it's a better shot than most would have at it.