I meant my comment more as "as someone who can taste the difference between certain things, it's really hard to imagine what it is like for people who can't" than a general "I can't believe some people can't tell the difference between how some things taste!" I don't think people are lying or stupid or anything else, just that it's hard to imagine. The color-blindness analogy in another comment is apt I think - if you can see color differentiation, it's really hard to imagine not being able to.