The percentage also gives us some idea about the chocolate's sweetness. If a dark chocolate contains 70 percent cocoa mass, it must contain about 30 percent sugar. The chocolate will have an intense chocolate flavor, with just enough sugar to make it palatable. The lower the chocolate's percentage, the higher the percentage of sugar and the sweeter the chocolate will be.
To avoid paying top dollar for a bar of chocolate that could pass as a bar of soap, purchase a reputable brand. Better quality chocolate bars have fewer ingredients, usually only five or six, and use real vanilla (not vanillin or other artificial flavorings).