10. Cats usually don’t wag their tails as a sign of happiness like a dog does.
Most people think it’s cute when they see a dog wagging its tail excitedly, like when it’s receiving a treat. However, we usually don’t notice a cat wagging their tail like that. Think about it: when was the last time you got home, and your cat wagged its time in joy? Now that may be a reason why some people prefer dogs over cats, and vice-versa. A happy and content cat usually does not move its tail very much, if at all. However, a distressed cat will switch their tail back and forth sharply as a warning sign (via Ranker).
It doesn’t always mean, though, that your cat is in distress or ready to attack. Some actually do wag their tails when they are getting attention. Maybe they are swaying their tail to encourage you to continue petting. In order to be able to really tell if your cat is doing it due to happiness or because it is distressed, look out for other signs of aggression it may also display, such as flattened ears or hissing (via Benton).