In my language 'nonsense' is impolite enough and used in expressions of disgust usually towards people and events. But I see a lot of people here often use this word while explaining others' that there questions and the likes have no basis.
Your assumption is wrong. ... [explanation of what is the right thing] ... So this is nonsense.
This is contrary to their entries in other meta posts or comments elsewhere where the same people are supporting SE's 'Be nice' model.
Is it actually an impolite word? I'd like to know about its usage in both British and US English.
Research: Couldn't find any credible website writing about its usage.