I ran across this article which I found to be very informative. It talks about what consistency (softness) is considered healthy for your cat's stool. Also of interest is the Bristol Stool Scale. It is a rating system which describes the softness of the stool and attaches a number to it. This way you can talk to your vet about your cat's stool and make sure you are both on the same page as far as how soft it is. I showed the chart to my vet's office, and they said it is a widely used scale. (They added that there are others, although they did not mention specifics.)
http://www.floppycats.com/cat-const...tment-of-constipation-with-dr-jean-hofve.html
http://www.floppycats.com/cat-const...tment-of-constipation-with-dr-jean-hofve.html