Mr. Brooks, a 38-year-old consultant for online dating Web sites, seems to be a perfect customer. He publishes his travel schedule on Dopplr. His DNA profile is available on 23andMe. And on Blippy, he makes public everything he spends with his Chase Mastercard, along with his spending at Netflix, iTunes and Amazon.com. “It’s very important to me to push out my character and hopefully my good reputation as far as possible, and that means being open,” he said, dismissing any privacy concerns by adding, “I simply have nothing to hide.