I've worked in a few places were the tenant has died and not been discovered for a while (thankfully, the body was gone before I got there), and I've also reported possible deaths due to the smell coming from various flats and houses.

But the worst one was were the guy had died in the shower and a fair bit of him had got washed away, that place REALLY stunk

Too old to die young, too ugly to leave a good looking corpse