I'm going to call out my customers for bad handwriting
Why do you want to call them out for their handwriting?
I just want to be that mean
People shouldn't be rude to someone over something as trivial as handwriting. Doing this will upset the customers and make them not want to come back. Instead, find ways to make your customers feel happy and satisfied with their experience!
Whatever, just saying I wouldn't want to buy from someone with bad handwriting.
It can be frustrating to deal with bad handwriting when trying to read someone else's writing, but it's a rather minor thing. I think it's best not to let it bother you too much. Everyone has their flaws, and for some people that's their handwriting. If you find yourself feeling frustrated, take a couple deep breaths to calm yourself down.