Hello Airborne,
Any time you notice excessive drooling and an abnormal odor from a cat's mouth, odds are there is either a viral process going on like Feline Leukemia, Feline Calici Virus, or some degree of Periodontal Disease.
I would highly recommend that you have your pets seen by your vet. For them to be so YOUNG ( 1 year ) , I would not expect severe dental disease, so I would be more worried about severe gingivitis or stomatitis secondary to VIRAL disease of some nature. As viruses are contagious, there is a high probability that several of your pet's could be affected with the same problem.
For more info on Excessive Drooling in Cats, please feel free to explore the following links:
http://www.manhattancats.com/Articles/drooling.html
http://www.catloversvet.com/catflu.htm
http://www.funkstownvet.com/dentalcleaning.html
Get your kitties in to have proper oral examinations and dental evaluations as soon as possible. Your vet may need to prescribe antibiotics, antiviral meds, or oral rinsing solutions to help solve your pet's oral dilemma!!
Please remember to PRESS ACCEPT for my prompt and professional attention to your concerns for your pets. I am thankful for feedback and appreciate any type of bonus!!
Best wishes, Dr. Jodi Lynn Smith
Veterinarian
Veterinarian in Small Animal Practice for 12 years