Sometimes it has a specific taste/smell, sometimes it doesn't and not much can be determined by either factor.
It just tastes like drugs. Not going to taste good ever, just a weird chemical taste thats going to vary from batch to batch and purity to purity. Name a drug that tastes good and doesn't tastes simply like, chemicals.
I have some right now that has that EXTREMELY STRONG smell of black licorice, which I hear is common (correct me if I'm wrong, but a specific production process produces MDMA with this smell?). But I wouldn't ever take that as a tell tale sign of what you have is MDMA, although it might be reassuring.