There are many smells we all collectively hate – POOOOOOOO. Rotting meat. Formic acid, produced by ants and other insects as a deterrent. Smoke. These are explained by a basic wired-in instinct probably evolved through natural selection, where detection of those smells induces an avoidance response. Avoiding such things could save one’s life! To not avoid smoke or poo with lots of diseases in, etc could KILLLLLL you.
Some people hate some smells more than others. It isn’t always clear, but sometimes it could be a psychological thing (negative conditioning – a smell based on a bad experience). Sometimes the smell might be annoying to someone because it is more like noise to their, distracting them – such as someone eating hot food on a train. A smell might be of food that makes someone sick. Sometimes someone will hate a smell merely because someone they know doesn’t like that smell.
Its always something that is either nature, nurture or a mixture of the both. Scientists often have to work against all these sometimes when working on different projects. Only today I had to work in a stream that smelt very bad.
Thomas already covered most of it 🙂 I will just add that we all also tend to remember smells very easily…. Who cannot remember the smell of that favourite dish? Or dirty socks in a bad day? This helps in creating an association between a smell and a memory, so sometimes you will hate a smell based on the experience that we had on that smell and not the smell itself! Did it never happen to you to hate a smell and not knowing why? However, you can always say that it smells like something you know, in spite of not knowing what!
Yep Sofia and Tom make really good points!
I think I’ll just add a bit about the fact we are all born different in how we can smell. There is one gene that can completely change the way you smell things! Depending on which type of this gene you have completely changes how you smell malt, apple, blue cheese and violets!
Everyone has slightly different receptors (the things that detect smell).. because we have 400 of them!! So smell is a very complex thing.