I judge books by their covers almost every single day.
I happen to mean this literally: every morning, I get an email from Amazon with special offers on Kindle books. And unless I spot a book that a trusted source had previously been recommended to me, I choose which book images I'm going to click on to learn more about (and consider buying) based entirely on their titles and how their covers look.
Why? Because I simply don't have the time to click on every single book cover featured in that email, read every description offered, and carefully consider which of the books I might purchase... especially since all the books are offered at $4.99 or less.
Am I missing out on some really great books that have names I find awkward or covers I think are initially unappealing? Almost certainly.
But when you're literally judging books by their covers, the risk of getting it wrong is fairly low: the worst that can happen is you miss out on a great read.
That's not the case if you use the same flippant approach when evaluating people.
If you judge people based on how they look (or speak, or dress), the risk of getting it wrong is much higher: you can miss out on exceptional talent that might have the different perspectives you need to drive your business forward while leaving someone with a poor impression of you and your brand.
Getting to know someone well enough to develop a fair impression of them takes time.
But people are not books.
More often than not, the extra time required will be time well-spent.