I wanted to add that our cat Sophie had bad breath when I got her from the shelter at 7 months of age - I figured it wasn't her fault and I'd love her anyway. She was very skittish, and mostly hung out under the bed. The shelter said she was born feral, so I figured this was the way she was going to be. She also had a really weak, scratchy meow and hardly purred at all.
I took her to a vet when I got her, the vet said all was OK. At about 1 year of age, she had become increasingly more congested in her head, and when you listened to her sleep you could hear she was having trouble breathing.
So, I took her to another vet who determined she had raging gum disease. Her gums were so infected at 1 year of age that four of her teeth had fallen out. Vet had to put her under and cut off the diseased tissue and pull some loose teeth.
I shared all of this because I want to stress the importance of cleaning their teeth, especially if they're predisposed to this type of condition. (Our vet said Black & White cats get it more often (?)) Sophie doesn't love having her teeth cleaned, but she tolerates it. Now she can breathe easy, meow clearly and purr often. She hangs out with us and plays like the young cat she is.
The point is that I never thought about providing dental care for a cat, but it has totally improved her quality of life.