My chocolate creme flavour doesn't taste sour at all when mixed with water or milk. Tastes completely acceptable. I wonder if what you have and what I have are even the same after hearing your comments...

Mine just tastes like a slightly more synthetic chocolate milk shake.

Mine tastes quite sweet. I don't have any frame of reference since this is my first protein powder so maybe it is less sweet relative to the other brands. But definitely not sour.

From what I gather here both musclemania and Eji are reputable sellers. I'm also wondering if my protein is fake seeing that it tastes better than what all you guys describe. Hahah