Walmart's social-media chief has 5 million Pinterest followers. Walmart has only 137,000, so she clearly sees room for improvement. And one of the brands she sees doing best there is rival Lowe's, she said in a talk Thursday at the Brandemonium conference in Cincinnati.

Such conferences are full of show-and-tells from executives about their brands' own successes, but Walmart Senior Manager-Social Innovation Christine Martinez Loya focused mainly on what others are doing well, and her own largely pre-Walmart experience as Pinterest's user No. 8 – which she became seven years ago thanks to an invitation from the founders at a conference for design bloggers.

Loya was also frank about Walmart's challenges in social media, despite the company generating 5 million comments a year across platforms. "We do have a small challenge," she said, "which is changing Walmart's brand perception. No tiny endeavor. It's a massive one."

Loya is part of a newly revamped social-media team based in San Bruno, California aiming to do that. Pinterest is a big part of how she believes it can happen. She literally wrote the book on the subject -- The Complete Idiot's Guide to Pinterest Marketing, published in 2012. She also acknowledges that after a recent reread, "half of it is totally irrelevant now," though it's still useful from chapter six on.

Pinterest is potentially powerful for Walmart and others because it reaches seven out of 10 moms and half of millennials (mainly the female half) in the U.S., she said, in a largely positive environment.

"Sixty percent of Pinterest users believe it elevates their lives," Loya said. "I'm not sure how many people can say that their Facebook feeds elevate their lives. Or their Twitter feeds. Especially these days if you follow certain people on Twitter."

Pinterest isn't a social-media platform, but rather "the world's foremost search engine for ideas," she says. That means people are using it often to find things they might buy.

Loya warned against "pandering to the platform" by, say, pinning content about weddings to sell vacuum cleaners.

Lowe's, with 3.4 million Pinterest followers, excels at Pinterest among retailers, she says, by focusing on their "core commitment to customers," which is home improvement. Pins are heavy on do-it-yourself tips, seasonal content, tutorials, makeovers and party planning.

Walmart, she acknowledged, has mainly treated social media as a means for distributing conventional digital advertising.

"There's an emphasis from larger corporations like Walmart on those heavily targeted, high-performance campaigns," Loya said, "and they haven't necessarily taken the step back to look at these platforms to be opportunities to be great storytellers." Part of her role on the social-media team is to do just that, Loya says, and largely by soliciting content from customers.

"We're looking for a lot of great user-generated content, really looking to have our customers lead the way in helping us change our brand perception, because of the wonderful experiences they're having, because of how important Walmart is to their community," she says.

Community involvement is Walmart's "key differentiator" in social media, Loya says. "Our biggest competitor in this space is Amazon. Amazon is very tech-focused, almost robotic. We see ourselves as being very people-oriented. We are integrated into every community across the U.S. and around the world."