Just a patient-What you experienced is not unique to just nursing, you have/will encounter people like that everywhere. We have all talked about others, I have done it. Was the nurse out of line, in my opinion yes. I have a feeling if that nurse heard someone talk about her like that she'd have a major problem with it.
I curse but that is one of few words I don't say. Using the word she used was very unprofessional, especially where a large group of people can hear her. In my opinion a person using that word to describe someone is immature. Talking like that is no way to gain respect it's, an easy way to lose it.
However, it's how YOU choose to respond to a situation like that. In the case you witnessed the nurse who she was venting to choose not to respond. She very well could have been laughing at the nurse for talking like that and wasting her energy, and chose not reply.
I'm disabled due to CP and in a wheelchair. I've had people tell me being in a wheelchair is easy, that having all of the operations I had were easy, I could go on. What it has made me think about is how NOT to speak to others.
I can tell you as someone who usually had a room by the nurses' station I have
heard nurses talk about patients', it was usually the ones who were being unreasonable or nasty towards them, and they did not use such strong words. In the end be the nurse you want to be and others to look up to. Hope this helps.