People tend to calm down and believe you more.
According to psychological studies, cursing can be beneficial when trying to develop trusting relationships with someone. When I am giving someone a reading, it is important to me that they find me authentic. Now of course I can do this without cursing, but sometimes I just have the urge. People who curse are statistically considered more honest and trustworthy. When you curse to some people you seem instantly more "real" and they start to relax. Now, this isn't the case for everyone and that is perfectly alright. But sometimes it works and it works well.
Life can be messed up.
Let's be honest. Sometimes things are bad. Really bad.They just are. When doing readings, us tarot card readers have an obligation to tell our clients the truth about what is coming up. Sometimes, things aren't good. And sometimes we express things that aren't good with language that expresses that. But we can also use cursing to bring humor to a bad situation. Have you ever cursed to make a joke when someone is upset and they just look at you crazy but start laughing? In that moment, that 4-letter word brought them some comic relief that they definitely needed. I have many clients laugh through their tears and that always makes both of us feel better.
Enlightenment comes with knowing there is still a dark side to everything.
When you become more "enlightened" or "conscious", it does not mean everything is now fine and all the problems you have ever had have melted away. To be enlightened or conscious is to also be aware of what is happening around you, but being able to handle it and accept it. Of course there will still be times you are angry or sad, and expressing that does not make you a less professional or spiritual person. It makes you human. Which brings me to my last point.
You can't live "up there".
In may cases, cursing can show you are human. No matter who we are, we are all the same people. We come to Earth with feelings and a slew of messy emotions. Walking around with our heads in the clouds talking about Spirit and Angels all the time makes one seem like they are ignoring the real issues people are dealing with. Your need to come back to earth and deal with what is going on here.
So in conclusion, if your still worried about how you are speaking with your clients in regards to cursing, gauge the situation or better yet, just ask them. If they would prefer you not curse, they will tell you and they will appreciate your consideration for their comfort. Now go forth and be awesome, damn it!