Fortune-telling, you see, is a give and take between the diviner and that which would be divined. If it is something that you think you want to know, the teller would be unable to answer. The limits of one's abilities, with all of their power, should never be forgotten. It is the same, no matter the business. Lying because you can't see, or aren't able to make out the form, conducting yourself as if you can do something you can't, is just rude to those who are serious.