If you think you're gonna fail it more than 20 times, I suppose.

BTW, the best way to clean a keyboard is to pop it in the dishwasher. Done it many times, and as long as it's not a $5 keyboard, it'll hold up just fine and be squeaky clean.

Also BTW, this sort of crap is why I personally hold no esteem for certifications. They don't provide any knowledge to an employer about whether or not a potential employee has the appropriate knowledge, as they don't test appropriate knowledge. In fact, I tend to toss out on their ears the interviewees who are proud of their certifications, as they were unable to recognize that the certs are useless.