With BP's deadly Gulf of Mexico disaster making headlines all over the world -- and the massive slick making its way to the coasts of Florida and Louisiana -- experts everywhere are scurrying to calculate the damages to everything from fish and birds to jobs and revenue. And while it's straightforward to calculate the $25 billion BP has lost in market value since the explosion, measuring its annihilated brand value is trickier. "Since the accident, BP has gone from being No. 1 in its category in our brand loyalty index to dead last," Robert Passikoff, founder of Brand Keys, tells Marketing Daily. "Today, reputation is your brand positioning minus what you've been caught doing. That is exactly what we are seeing here, and BP is in a lot of trouble." Branding expert Lisa Merriam agrees. "The much-admired green sun BP brand died this week," she tells us. "This is a brand that never left the marketing department. No matter what they said the company stood for, they never lived it. Despite all those smug ads about wind farms and being 'Beyond Petroleum,' this shows they are just like any other oil company -- their green brand is as dead as all of the wildlife washing up on Louisiana shores." Particularly galling, says Merriam, who runs Merriam Associates, is its slow response time. "They put all this emphasis on 'human energy,' and where are the humans now? It took them seven days to get out a Twitter response, and it's so corporate and robotic. If you're going to brag about how honest and open and responsive you are, you have to do that -- would it have killed them to run a Twitter post that said something like, "Our hearts go out to the friends and families of those lost in the accident," or "We are working around the clock to contain the damage"? While BP is on the hook for the massive cost of cleaning up the spill, which some experts say might be bigger than the 1989 Exxon Valdez disaster in Alaska and which is spewing an estimated 5,000 gallons a day into the water, whether any of this will make a difference to consumers, she concedes, is another story. "There's lots of research that shows that people won't even cross a median to change gasoline brands." Investors, however, are more likely to shun the company, says Passikoff: "Investors are more likely to buy stock in companies they trust." But among its larger audiences -- thought leaders, legislators and regulators -- the damage is likely to be vast. In much the same way that it would be dangerous for an airline to plug itself one that never crashes, Merriam says, BP's positioning made it especially vulnerable for this type of fall-from-grace image debacle. "The problem is that oil is a very dangerous and dirty business," she says, "and to build their brand on a green positioning was always a risky thing."