It’s a beloved truism in publishing that the cover is the key marketing tool for a book. Even those outside of the industry know the cliché, “Don’t judge a book by its cover.” But, in fact, we all make snap judgments about whether we’d enjoy books based on looks alone. It’s not so different from shopping for clothing or anything with a distinct look and feel—some things match one’s identity and others don’t.

That’s why it drives me a little nuts when authors post their covers in progress on social media groups full of other authors and ask for feedback. This tends to happen for one of two reasons. Either the author is unhappy with the cover she received from her publisher—and seeks validation or support in requesting a new design—or she’s trying to decide between multiple cover options.

Those crowdsourced opinions have an approximate value of zero in determining the best cover. Here are three reasons why:

1. The crowd hasn’t been part of the book’s big-picture marketing and packaging discussion. No meaningful cover discussion can occur without an understanding of the initial cover direction and why that direction was established. Unfortunately, this may lead to an uncomfortable realization: the author doesn’t know what the cover direction is or didn’t establish one. If that is the case, it must be remedied before any intelligent cover discussion can happen. At the very least, an author needs a firm grasp on the genre she’s attempting to fit into and what strong sellers look like in that genre.

When I work with self-publishing clients, one of the first things we do is assemble a cover brief. This brief establishes the genre or category, describes themes of the novel that might affect the cover’s aesthetic, and points to other covers with the aesthetic that we’re shooting for. That gives us a very clear way to, first, choose an appropriate designer (someone with experience in creating covers for the genre or who has the right design sensibility) and, second, evaluate whether the designer has achieved the goals of the cover.

How the book will be primarily marketed and sold can also play into the cover design brief. For example, commercial fiction or books heavily marketed through Amazon will often feature clear, crisp designs with high contrast. The names of bestselling authors may outweigh the titles of the books. Books marketed more to high-end readers—take The Meaning of Life from the School of Life as a recent example—have covers that are downright unfriendly to online display. But School of Life books are mainly marketed to those who know the brand already, and they may be buying direct.

2. The author crowd doesn’t represent readership. They will have their own aesthetic judgments and biases, and they may have little in common with the readers whom an author is trying to reach. Worse still, an author may not know the experiences or backgrounds of the people offering opinions. That’s common when surveying a large Facebook group consisting of thousands of members.

Of course, there may be scenarios in which surveying the crowd is a wise decision, like when asking readers for feedback. Even then, exercise caution. If fans sense that an author wants them to react in a particular way, they will. Try to ask open-ended questions such as, “What feeling does this cover evoke?”

3. Cover disagreements with the publisher shouldn’t be taken to the crowd for a verdict. If authors are unhappy with the covers from their publishers, author groups are more likely to offer support than contrary opinions. But seeking validation isn’t going to help an author secure a better cover. Quite honestly, publishers don’t care what family, friends, or social media circles think about a book’s cover. But they do care if the Barnes & Noble buyer is unhappy with the cover—or if they believe the cover is not appealing to the target audience. (Tip: preorder marketing or advertising campaigns can be an early indicator if the cover is off.)

For my most recent book, The Business of Being a Writer, I was not happy with the first cover design from my publisher. It’s not that the cover was bad, but I believed the aesthetic conveyed all the negative stereotypes that writers have about business. I wrote to my editor explaining my reservations and why I thought it was sending the wrong message. Thankfully, the second cover design better captured the essence of the book.

Though there are many areas of writing and publishing in which it can be helpful to brainstorm and solicit feedback from within one’s social circles, an author’s most important marketing tool shouldn’t be left to a random vote. Smart authors must remember to be intentional, focused, and reader driven when making decisions.

Jane Friedman teaches digital media and publishing at the University of Virginia and is the former publisher of Writer’s Digest.