It is rude to comment on people's personal hygiene.
Sally is in the break room at work getting coffee and chatting with coworkers when Sam walks in.
Sally wants Sam to join in on the conversation she's having.
Sally tells Sam that she should hang out and chat for a bit before heading back to work.
Sally remarks to Sam that she must have a had a rough week because it looks like she hasn't showered in days.
Sam agrees and ends up having a friendly conversation with Sally for the next several minutes.
Sam is offended by Sally's comment and exits the break room as quickly as possible.