In order to understand what smells do cats really hate you have to first start at the cat's physiology. Most people assume that cats and dogs both share the same list of scents that they dislike. This is a myth. Once you understand the smells that cats dislike you will be able explain their behaviors and be able to provide better care for them.
Cats are able to understand the world by their sense of smell and taste. They both work hand in hand. All cats are born with an organ specially designed for scent called the Jacobson's organ. The Jacobson's organ transmits signals directly to the brain's receptors and is what allows the cat to distinguish the scent. Another interesting fact about the Jacobson's organ is its connection to aggression and sexual behavior in cats. Cats also have millions of olfactory sensory cells that retain the scent in the cat's nose above the subethmoid shelf and allows it to continue breathing while the brain is analyzing the scent.
Now lets get on to what scents really stink for cats. Cats really dislike anything with a citrus scent such as lemons, grapefruits, and oranges. It is unfortunate because I adore the smell of all citrus fruits especially from from the essential oils in the citrus fruit skins. Of course cats are not humans so they are not going to share the same likes and dislikes as humans when it comes to scents. Cats also do not like spicy scents such as cayenne pepper and mustard. Also avoid using chemical products around your cat because they will really irritate them especially when you are trying to human train the cat. If they are constantly smelling chemicals around you they may always associate that scent to humans and eventually try to avoid you entirely. There are some deordants that cats also dislike and as an owner you have to be careful when purchasing cat liter that contains these deodorant scents or otherwise the cat will refuse to use the liter box making it a disaster when it comes to potty training cats.
Cats sense of smell is so important. It is one of the most important ways it can understand the world around it. It is very senstive to certain smells so if you want to have a properly behaved house cat you need to test out smells that it will like around you. Bad smells can be imprinted in a kitten and if you are not careful it will remain with the cat for life. If that happens and one day you expose that cat to that smell it can become aggressive or frightened. However, all cats have their uniquenesses and a scent for one cat might be the most horrible smell in the world, but for another cat it is perfectly tolerable. Just be aware of the common scents that cats dislike such as citrus and spicy smells. If you stay away from these scents you will be able to raise a healthy and happy cat.