People I truly love and enjoy as performers sometimes make huge mistakes when it comes to symbolism and things outside of their own realm. Those mistakes may seem like brilliant ideas to other performers not well educated in the tools they are using.
Mentalists especially (though magicians too) have been told to "just make things up" in popular books on performing with Tarot and other symbolic tools. "It's all made up anyway!" is their argument.
That's akin to an atheist saying "Just make up what's in the Bible because it's all made up anyway!" Maybe that is the atheist point of view, but that is not the point of view of those who study the Bible.
You never know how many Christians, for instance, are in your audience.
If you say that, "In Bob 3:14 of the Bible it says..." people would laugh out loud, or shake their heads at your supposed Bible expertise.
The same is true of many other belief systems mentalists and some magicians like to toy around in.
So, unless it is your performing purpose to upset people, or unless you could care less about showing your own ignorance, you either need to educate yourself about the tools you use in performance, or simply not use them.
That is true of Tarot, but it is also true of "mystical symbols" and terms such as "Mesmerism" or "NLP".
You might well be fooling yourself and those authors who tell you to "just make things up" when it comes to Tarot, readings, and more symbolic things, but you won't fool for an instant anyone who has a respect, belief, or studied interest in such matters.
And you never know who in the audience has those interests or beliefs.
That's why some of my friends have a code to each other when watching performers talk about things they have no real knowledge about:
"Bob 3:14" If you read the above, now you know why.
So be prepared, or if you want to be lazy about it, don't use tools you know little or nothing about.