Their images intrigue some and frighten others. But they are only paper, ink, and sometimes plastic coating. They're used by people looking for a direction in life, and they're used to entertain kids at a party. Such diversity!

The interpretation of a single card can contradict from one dedicated reader to the next, so how can they be used with any reliability?

They are a tool, designed for a specific purpose. Their reliability is entirely dependent on the reader and how these tools are applied.

Anyone can wield an axe, but whether they use it correctly and for a correct purpose, can make all the difference in regard to its value.

Tarot when used correctly is not meant to predict the future. That is not their correct purpose. They are a counseling tool, and serve to bring concerns into focus in order to aid the querent in making decisions. It is possible that they may suggest in their content what MAY happen if a certain path is taken and what you might end up with in the process, but they will never tell you what WILL happen. If someone is predicting the future using Tarot cards, then they are either:

1. a psychic using them for aesthetic purposes, or
2. a complete fraud.