A famous demonstration of differences in tasting ability involves phenylthiocarbamide(PTC). For most people PTC tastes bitter, but there are many people for whom it has no taste at all.
This difference is genetically inherited for the most part, although there are cases of identical twins in which one can taste it and the other cannot.
There are also people who cannot taste vinegar. Some taste mannose (a type of sugar) as sweet, others as bitter or salty.
Icicle: Those strips of paper most likely had phenylthiocarbamide or Sodium Benzoate on them.