One of the best pieces of advice I ever received from a professor when I was in college was totally unexpected. When we were first year and learning about doing intakes, she cautioned us to be prepared for meeting people who smelled bad.
In our line of work we are often meeting people who have poor hygiene (for various reasons) or who are living in spaces that are not clean, and therefore smelling a lot less than fresh.
It was a quick off-handed comment for the professor to make, but something I totally had not considered up until then. I think it prepared me to handle some stinky situations with more grace than I may have otherwise, and certainly reminded me not to pass judgement on someone for their olfactory state.
Eight years later, if I had a dollar for every time I've written "malodour" in a note...