Sometimes I struggle with this, so I understand completely. Too often people pile on the accolades and exaggerations that aren’t reflective of the experience at all. And, some people have a tendency to be vague and complimentary to glaze over any unpleasantness by expressing how “amazing” the client is or how “great” it was to work with them.
You don't want to do either- It’s disingenuous and beneath you. So, it's good you see the value of this business practice. There are some etiquette guidelines about that can help if you follow them. As a young professional or entrepreneur don’t underestimate how important it is to recognize and appreciate others even when you may not feel like it. You never know who they might know or when your paths will cross again.
Here’s my advice and what I recommend if you want to write a thank you note that is authentic and specific. It’s not that hard, totally painless, and will be second nature to you once you get the hang of it.
Distance yourself emotionally from the situation. You don’t need to send a thank you note immediately. You have some time. If you are thinking about it or obsessing, stop! Get it out of your mind for awhile. If you keep talking about this horrible experience, quit it. Just let it be and breathe. And, let me be clear, I am not in any way referring to situations of harassment.
Look at the positive
When you can be objective, take a few minutes to focus on the positive aspects of the work experience and the client relationship. It may be difficult, but there is something there. Likely two somethings. Are there any good qualities about this client? Did this experience benefit you in some way other than payment for services rendered? You could be a wedding photographer who had to put up with a rude, demanding bride, but the way she looked at her groom during the First Look session was pure magic. That’s your thank you note. As in:
"I know choosing a wedding photographer is an important decision. I appreciate you trusting me with that responsibility. I must say, I can't recall a First Look session that captured such magical expressions of love. I'm happy you let me have a glimpse, and I wish you much happiness."
Don't stress about writing a lengthy note. You only need 3-4 sentences, but you want to make the words genuine and specific. People love to be recognized and appreciated. It’s kind of a universal thing. Here is an example you might edit and use that addresses those two needs:
I want to thank you for the opportunity to work with you and your organization. I was so impressed by how you handled this massive organizing effort and the sheer scale of it all. The final product was breathtaking, and I’m grateful that I could be a part of that effort.
And just like that you’ve done it- short, simple, and to the point.
All the best to you and keep in touch!