Do you have a lot of cavities? Perhaps it's because you lost a lot of enamel sucking on sour candy when you were a kid. It's almost as bad as battery acid—except it tastes much better.
Take a look at this chart and see who are the worse offenders.
Pure water's pH level is 7, which is a neutral acidic level. At ph4, your teeth start losing enamel, one of the four tissues that make up teeth. Enamel it's the hardest substance in human bodies. 96-percent is made of minerals.
As it turns out, typical sour candy is ph3, which is kind of crazy. It quickly goes to ph2.5—with Skittles, Baby Bottle Pop powder, Brach's Gummi Bears, and Sqwigglies Gummi Worms—and 2.4 with Mentos Fruit Chew and 2.2 with Sour Skittles.
But it gets a lot worse. These are the three worse offenders—Altoids Mango Sours score a ph1.9 while Wonka Fun Dip Powder gets down to ph1.8. The worst is WarHeads Sour Spray, only 0.6 less acid than battery acid. [Northwest Dentistry via Kottke]