An NPC cast spores on me. I went and sat in a hot room and the duration was halved twice, then, when it was around 11 hours, it stopped being halved on each tick. I left the hot room. When it eventually wore off, I got the echo you get on the tick when spores affects you plus the wearoff echo:

You feel a burning sensation on the inside of your skull.
You are hungry.
You breathe easier as the spores scatter.

For every other affect I'm familiar with, on the tick when the duration changes from "0 hours" to "not present in your affects" you only get the wearoff echo.