They are quite literally 'accidental' - the triangle could have just as easily been a different set of proportions. At consecration, something which the Church calls 'trans-substantiation' takes place. The accidents of the bread remain the same - the way it looks, and so forth. The same thing happens with the wine. Once it's changed, it's changed forever.
Nothing can reverse it.
It's like making a triangle into a square - something quite fundamental has happened, which means that you can't go on pretending it's a triangle. So, no, the Body and Blood of Jesus doesn't taste like flesh or blood. Jesus knew how squeamish we were, and so instead chose, for the sign and vehicle for this wonderful gift of Himself, bread - the most common food of most people in the world, in one form or another, and the 'staff of life'. And it's not horrible at all, but very humbling - God Himself gave us His own Body and Blood to eat, so that we might truly have Him living within us. He feeds us with His own self.