Cats wind up in shelters for a lot of reasons, and very few of them are "because s/he was a bad cat." People lose their jobs, or move away and don't take their pets. Kids leave for college. People die. People lose the wherewithal to feed themselves, much less an extra, meowing mouth. And in all of these cases the cats, who have no idea what's going on, wind up suffering for it.
Amazing cats come from shelters. Adult cats who don't need to be trained; kittens who have all the world in front of them. Cats whose personalities are already plain when you meet them, making it so much easier to find the right cat for you. Cats who need you.
I've been very upfront about why none of my current cats are from shelters, and why my lifestyle and emotional needs are better met by reputable breeders. But if you don't fall into this category, and feel that there might be a cat-shaped hole in your life, go and take a look at your local shelter.
This post brought to you by the California Dammit Why Can't I Take Junebug Home Oh Yeah Alice Would Kill Her To Death Committee.