[sm64]

To add, the "no sugar added" thing is wholly misleading because there are fruit concentrates that companies can add that are basically sugar substitutes. It's technically not "sugar added" but it's basically filled with healthy dollop of fructose (which is worse than sucrose but I'm too lazy to cite a reference).

[forgotpwagain]

Grape juice is the notorious one here. It doesn't have a very strong taste on its own, so when blended basically serves as a not-technically-added-sugar source of added sugar.

[gnicholas]

I recently saw a ginger-flavored carbonated that boasted of the percent juice. I was surprised by the number (30%?), and when I looked at the ingredients I saw that the juice was not mostly ginger. It was grape juice.

I understand that when I see “cranberry cocktail”, there’s a bunch of sweet juice mixed in. I didn’t realize that drinks of other flavors have so much clandestine grape juice — which is basically sugar.

[dunham]

I've also seen apple juice used as a sugar in "100% juice" drinks.

[anothergoogler]

Yep, buy something like "kiwi-strawberry-guava" juice, apple or pear juice is usually the first ingredient. I wouldn't be surprised if most juices are flavored versions of the same base.

[BrandoElFollito]

This depends on the country.

In France the wording 100% juice mans that that the liquid is directly from pressed fruit. No concentrates, nothing added. The only operation can be filtration and pasteurization.