When chocolate looks gray and streaky or dull on the surface, or when the interior looks crumbly, the chocolate has "bloomed." Bloom is caused by moisture or temperature fluctuations, but does not mean the chocolate is spoiled. Melted for recipes, it behaves and tastes like any other melted chocolate.
Bloomed chocolate is also safe to eat as is, but its texture may be grainy, and it may be less flavorful. If you have a choice, melt and use bloomed chocolate in a recipe. Otherwise (and most chocolate lovers would agree), bloomed chocolate is surely better than no chocolate at all for other purposes.