As it turned out, people played along pretty much as he'd intended. A lot of people played along, in fact. The card went viral, up to and including its being the topic of a Penny Arcade strip. As the strip indicates, clearly, not everyone was totally pure-hearted about it, but then, this was a social experiment, and you have to account for that possibility. And it did cause a lot of the users to carry on the pay-it-forward nature of the exercise.
And it would have probably just gone on as such, had Jonathan's Card not also attracted Sam Odio, who had an exercise of his own: write a code telling him when the balance on the card got up to a certain amount, sit at a Starbucks, wait for the code to tip him off, and when it did, head to the register and transfer all the money on it to his own card. Over five hours, he had walked off with $625. Granted, this plan had a second phase- sell his card on eBay and donate the proceeds to the charity Save The Children, but it wasn't enough to make up for the fact that he'd compromised Jonathan's Card and ruined things for everyone else, who now had to worry about whether any money they were putting on the card was going towards coffee or towards Odio, and while some people supported Sam, most verbally unloaded on him. (The eBay listing was removed because of a rule that says gift cards for sale can't exceed a value of $500.)
Odio's older brother Daniel, meanwhile, was putting whatever money Odio took right back onto the communal card. Sam, catching a whole lot more flak than support from people offended by his actions, offered to hand back the money he took if Stark thought Odio was stealing; Stark responded, "My impression is not the one that matters. The impressions that matter are those of the people who have been touched by and participated in Jonathan’s Card. If you’d like to speak to them, you can do so on their Facebook page." The entire episode gave all observers and participants a pretty meaty ethical debate to chew on for a while; the second link in this paragraph shows Techdirt trying to work through that dilemma.
Besides, Starbucks isn't very good at doing its own viral marketing. In 2006, they e-mailed some of their employees in the southeastern US a coupon for a free iced coffee and told them to forward the coupon to friends and family. They did. Then the coupon got forwarded some more. And some more. And some more. And some very much more. And the coupon got out of the southeast in a hurry to boot. In almost as much of a hurry, the coupon had gotten out to so many people that Starbucks had completely lost control of it, so much so that they opted to stop honoring the coupon. This was not a popular decision amongst all the people who had coupons, which by now was quite a few people. One of those people, upon being refused a coffee, walked straight to a nearby lawyer and struck up a $114 million class-action lawsuit (no word on how it turned out). Meanwhile, competitor Caribou Coffee, who was at the time selling iced coffee of their own on a trial basis, announced that for one day, if Starbucks wasn't going to honor the coupons, they would.
A couple years later in 2009, Starbucks tried again. Operating on the theory that some people thought Starbucks was just an uncool place to go to and drowning out the mom-and-pop cafes in town, they decided to take three Starbucks in Seattle and, as a trial, strip all indicators that they were Starbucks shops, instead rechristening them as things like "15th Avenue Coffee & Tea" that were "inspired by Starbucks". Nobody was fooled for a second. Even if you change the decor, the locals are going to remember that there was a Starbucks there immediately beforehand and the employees are the same and the coffee tastes the same, and the dots are going to be connected pretty quickly. And if they weren't clear on the concept, the actual neighborhood cafes were all too happy to shout it from the rooftops. In 2011, 15th Avenue Coffee & Tea was turned back into a formal Starbucks. One of the three targeted for remodel didn't even get as far as the renaming. (As far as I'm aware, the other one, Roy Street Coffee & Tea, is still under that name, though it's widely known as the "stealth Starbucks".)
So seeing as Jonathan's Card was actually working out pretty well for them for once, until Odio came along, Starbucks was willing to look the other way on it. But now that the card had been compromised and the social experiment ruined, they pretty much had no choice but to let Stark know they were shutting down the card. That happened on August 12, a little under a month after the experiment began. Stark, for his part, looked at the bright side, noting on the card's website after receiving the notification from Starbucks:
We believe this is the start to a bigger more glowing picture. In the last 5 days or so, we've received hundreds of stories of people doing small things to brighten a stranger's day: Paying for the next car at the drive through. Sharing a pick me up with someone who has had a rough time. Charging up a phone card and sharing it with strangers at the airport. The list goes on, and on, and on...
So, tonight we lose our barcode. But of course, we never needed it in the first place.
As for Odio, Stark noted, "The card wasn’t hacked. He was standing in the store swiping the card just like anybody else." He was also critical of the notion that one person screwed it up for everyone, saying, "From the inside that's not how I see it at all. Tons of people were way more generous than I thought. Just because one person spray painted the mural doesn't make it a failure." Keeping in that vein, a Facebook page devoted to Jonathan's Card was maintained to direct people's energies toward related efforts, though it appears to have faded to silence in December.
And for the most part, the social experiment appears to have ended in success.