I don't buy strawberries very often, but when I end up with a few soft berries, they're still within the safe range for the guinea pig or the hamster to eat.

I do not, however, recommend getting a pet just to have a garbage disposal. Composting, worm bins, dropping berries for birds and squirrels, or making squishy paint are much better things to do with mushy berries.

Now that I think about it, I wonder if squishy strawberries can be frozen to use for baked goods later...? I know bananas can be chucked into the freezer to be baked, and blueberries will fare well. If you pulled out the ones that looked like they were about to go, froze them, then diced and baked them, I wonder if that would solve the original problem of having dead berries on your hands 3 days into a new carton.