I often look at a CV and notice specific skills that can benefit the business even if they aren't part of a normal job description. Imagine a software developer who used to be a graphic designer. I can save handoff time and have this person take on additional tasks, but it won't be in the job ad because the hit rate is too low. I can afford to pay that person more than others with comparable programming skills.

Or, I find value in areas that get overlooked in the market. Career transition people for example might not have many other options and I can take a gamble on how fast they ramp up.