What happens is sublimation, very cold air is very very dry and it sucks water (as well as other things) out of anything exposed (especially warm things), this is called freezer burn, when warm air cools off in the freezer everything in the air freezes out onto whatever is cold and deposits mostly ice on the cold surfaces. Water and other volatile compounds (like things you can taste) will move around, and temperature variations and inadequate protection from air will make it worse. Modern freezers also have an auto-defrost cycle to prevent ice build up on the freezer but this makes the problem slightly worse. I is generally unprotected in a freezer and has no taste of its own, so you can easily taste whatever was floating around in your freezer.