Vinegar and citrus probably are intrinsically acidic, but here's a quote:
Foods are classified as acid-forming or alkalizing depending on the effect they have on the body. An acid-forming food contributes hydrogen ions to the body, making it more acidic. An alkalizing food removes hydrogen ions from the body, making it more alkaline. It is important to note that this classification is based on the effect foods have on the body after digestion, not on their own intrinsic acidity or alkalinity (or how they taste to us). A common misconception is that if a food tastes acidic, it has an acid-forming effect on the body. This is not necessarily true. Very often, an acidic-tasting food is alkalizing. Citric fruits are a good example. People say that lemons, for example, are "too acidic"; however, they are actually alkalizing because the minerals they leave behind after digestion help remove hydrogen ions, decreasing the acidity of the body. (Many people use the term "residue" or "ash" to explain the effect of a food on the body. A food with an acid ash after digestion contributes hydrogen ions, making the body more acidic; a food with an alkaline ash after digestion removes hydrogen ions, making the body more alkaline.)"
I'm not a scientist. ACV definitely has an alkalizing effect on me. But these probably are acidic?