I use Carpet Fresh for pets..$1.59 at Publix...just sprinkle on the carpet (more in soiled areas) leave on for 15 minutes (I usually leave on for 30) then vacuum up...be careful to get it all up and do it while your pet is in a crate or somewhere away from the product, as things like that could cause an allergic reaction...

oh yeah, are you spraying your "spots'' with a vinegar/water mix right after you clean it up? This will help keep repeat offenses off the same spot