What is Tarot?
Tarot is a divination tool used to tell the future, but its more complicated that. I find that the reason many people don't believe in readings is because they don't understand that this form of divination looks at your life path as that of a snowflake. You start in the middle at birth and from there your choices in life fracture off and, depending on which choices you make, you end up with different outcomes.
Let's use this example of someone coming in and asking about when they'll get a promotion. Here are the choices you consider the next day that can greatly change your life.
All of these choices each have a varying outcome. Maybe if you walk to work you could end up being mugged. If you take the bus, you end up a little late. Stay home and you won't get the promotion next week. If you drive then you get a special surprise when you arrive.
It's which ever path you're currently on that the Tarot reads. Say you're a steadfast worker, always on time and you always make an effort to stay a little late to finish your work up. The tarot will divine based on your most likely choice of driving of getting there on time, as par your usual, and will tell you your hard work will pay off very soon in the form of a promotion that you've been asking.
Now, say you choose instead to take the bus, which is something out of character. So instead of it happening next week, as the cards predicted, and it instead takes a little longer than expected. Or, thinking that you're going to get somewhere in life soon, you decide to take a break against what the cards suggested, and stay home, missing the opportunity for months because that day ended up being a catalyst for this promotion to happen.
These things are what can make a reading "wrong".Obviously, in certain instances, you would hope it came out 'wrong' because you heeded the warning of something bad happening and took the advice given. So these are things to consider when reading for yourself, others, or having a reading done for you.