I used to be that way before getting into the habit of drinking water a couple years ago. I think a lot of it is just being used to drinking stuff with sugar, such that one’s tastes have long since adapted to that and then you notice and are disgusted by the lack of said sweetness in the water. I remember water seeming to have a sort of bitterness to it that went away after awhile when I stopped drinking sweet tea all the time and made myself drink water.