Many people love to attack Walmart — as the world’s largest company it’s an easy target. And although the retail giant’s green efforts have done a lot to showcase the company’s commitment to sustainability, sometimes Walmart gives its critics some legitimate ammo, like the recent revelations and allegations of corruption in its Mexican operations.

As the New York Times recently reported, in the early 2000s, when Walmart de Mexico was building stores at a furious pace (making the country the company’s second largest market), it was making illegal payments to get building permits and speed store expansion. The growth miracle was, it turns out, not so miraculous.

Of course this is not a good thing in and of itself. But where the story gets really troubling, if the accusations are true, is in how the company handled the matter. After its internal, FBI-trained watchdog group investigated the allegations — and made waves — the case was given back to the chief lawyer for the Mexican operations. This was, as the Times put it, “a remarkable choice since the same general counsel was alleged to have authorized bribes.” It sure looks like something not flattering, and possibly illegal, was swept under the rug.

So what do the recent allegations mean for Walmart’s sustainability efforts? On the one hand, nothing. In fact, the same week this story surfaced, the company released its 2012 Global Responsibility Report, an interesting juxtaposition to say the least. I’ve long been a fan and chronicler of the company’s green efforts (full disclosure: I’ve spoken at multiple Walmart events, including a sustainability summit held by Walmart Mexico in 2010), and this report did not disappoint on that front.

Walmart listed some impressive accomplishments, from diverting 80% of waste from landfills, to doubling the amount of local food sold, to generating over 1 billion kilowatt-hours of renewable energy onsite (the second most of any corporation in the U.S.). These achievements, along with a 5-year record of pushing the sustainability agenda harder than almost any company, are real and demonstrate leadership in responsible business.

So here’s the rub with sustainability, corporate social responsibility, ethics, and anything else that’s generally (if sometimes awkwardly) thrown together into the vast bucket of “good stuff”: The measurable and legitimately good things a company does will not make up for what it does wrong. But nor will the bad cancel out the good — the good things are no less legitimate just because the company does some things its leaders should be ashamed of. The good practices are worth emulating regardless of the larger context.

The significant challenge of how to view, judge, and learn from the actions of a complex, messy thing called a “company” is nothing new. If an oil and gas company wages a multi-decade campaign to muddy climate science, but also funds next generation low-carbon fuels research and operates incredibly efficiently, is that original campaign any less immoral? Should other companies avoid the cost-saving, innovative, best practices of the bad actor? Of course not. When it comes to what we can learn or gain from a company’s profitable and sustainable initiatives, the bad things don’t really come to bear.

But when thinking about a company as a whole and that vague thing called a “brand,” it’s a different story — everything is related. Key stakeholders, such as customers, consumers, employees, and even the investors and markets, judge the value and values of a company and then decide if they want to interact with it. That judgment so far is pretty clear in this case. Even though one can never have too much faith in short-term market reactions, this one was serious: Walmart’s stock dropped 5% when the story broke and, as of this writing, is down 8%, or $16 billion in market cap (while the Dow was flat).

I’m frankly surprised investors care — there’s historically, and unfortunately, little downside for companies that engage in this kind of corruption in developing countries. But the immediate market reaction here is fascinating. It says to me that there’s some recognition of real risk to the company in these practices: that the hit to the brand matters, or that people may not want to work for or buy from a company they can’t trust.

There’s some understanding that a company’s value in the market is connected to its values (of which sustainability efforts can be a good indication). Just as it’s not sustainable to over-consume natural resources, it’s not sustainable to alienate key stakeholders through ethical lapses.

The totality of a company’s actions does matter. We should demand consistent, ethical behavior and a real commitment to doing what’s good for people, planet, and profit, which includes not compromising on ethics. We can expect more from companies we buy from and work with and for, especially the very large ones that show such promise and leadership.

(This post first appeared at Harvard Business Online.)

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