This is actually a response to the dill pickle post where someone mentioned that vinegar has sugar in it. This really depends on the type of vinegar used. White distilled vinegar is acetic acid and in most cases does not contain sugar. Some brands will add burnt sugar for flavoring. Other types of vinegars such as cider, corn, flavored, do tend to have sugars present. (Cider vinegar which is sometimes used for pickling has 14g carb per cup).

Reading the label is the best bet.