system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why bad smells can usually last for weeks/ages but it is that difficult to make something smell well for weeks/ages?
gpt
Often, bad smells are caused by bacteria or fungii, which are living organisms that can reproduce and therefore be there for a long time, but something that smells nice ( perfume, food, incense... ) often comes "alone" (perfume) or from something that disappear, burns, or rot.

Therefore, to have a long lasting good smell, you need to have something producing that smell without deteriorating (flowers ? GMO bacteria, maybe ?)