Why don't fresh mangoes taste as good as frozen mangoes?

I bought Dole brand mixed frozen fruit, it has strawberries, peaches, pineapples, and mangoes. I love all of it but the mangoes are my favorite and they don't sell just a bag of frozen mangoes. I went to buy fresh mangoes, and bought 4. Two were really red, one was red/yellow, and one green/yellow. I went to eat one of the red ones, washed it and then started peeling it. The smell was so awful it made me sick. I thought maybe they just didn't smell that good so i tried it, and it was also awful. Why is this? The frozen fruit only contains the fruit, citric acid, and malic acid. No sugar.