You could be right, since something similar did take place as can be confirmed in one of the posts below (a large purchase for the homeless). But certainly we can agree that $15, $30, and $100 being drained in minutes to the exact penny must be cause for concern.
Edit: draining to $0.00 is OK, as jonathan explains below.
Draining the card to the penny is not weird. If there is $10 on the card and your purchase is $11.50, $10 will be removed from the card and you have to pay the remaining $1.50 some other way.
I see what you're saying, and of course it is possible that some jerk is buying gift cards with the card.
That said, it's worth pointing out that the tweet stream is not real time and it doesn't have every transaction. The card balance is scraped from the sbux site every minute and posted to Twitter if it has changed since the last tweet. When there are multiple transactions in the same minute, the changes get aggregated. This can result in some strange looking numbers.
What I think we're learning here is that if someone wants to reload the card, lots of little transactions over time is better than one big one. Or, perhaps the balance should not be tweeted.
Can you put spending limits on a card? Or disable it entirely?
What I'm wondering is if you can have a deposit-only card, which transfers funds to the live card to keep it topped up at $10. Downside is some people have to wait an extra minute or two for free coffee; upside is someone trying to clean out the account has to spread it over a bunch of transactions, which even if it doesn't stop everyone probably raises the barrier to entry.
A PayPal account could also work for this.
Then you could broadcast a rough total balance, and just have a binary indicator for when the live card gets topped up.
Thanks for your feedback! Your suggestion is a good one and something that I've been considering. It is possible to reload one sbux card from another, so I was thinking about using one for deposit only and dribbling the balance into the purchase card at $20 per hour or similar. I think there's something about this that would ruin the excitement so I'm working on different approach at the moment. Not sure where it'll end up.
I vote that you encourage people to make lots of little transactions over time versus just getting rid of the balance.
The balance is really neat to see and it keeps people engaged and thinking about this project, even if they're not actively partaking (like myself, at the moment).
The smaller installments of cash also help others realize that it's okay to submit small amounts and increase the likelihood that more than just one person with a large purchase will benefit.
Edit: draining to $0.00 is OK, as jonathan explains below.