I don't know

It is difficult to say hello with a smile. Sometimes I don't know if a person is feeling well. One day I went to the supermarket, and said hello to the cashier, she tells me What's good? It was a bad experience.
After that experience, I wait to get a smile before to say "hello".

Gracias por leerme.
Saludos

Honestly that person was completely unprofessional, and I apologize that you had to have such a situation. I wouldn't take it personally though. Sometimes saying hi to someone would actually help to brighten their day, so do not be afraid to reach out to people.