If you insist on using the free ads, there are some defense tips you can use when attempting to place your pet, but remember, you still have no guarantees that your pet will be cared for properly or will not end up in a lab being used for experimentation.
Ads Can be Hazardous to Pets.
Perhaps you are changing jobs, have experienced a decline in health or your new lifestyle means you can no longer care for your pet. The decision you've made for your pet could be deadly. Some people even use animals from the free ads as bait in training other animals to fight, as food for other animals, or in cult religious practices. After all, they said they wanted a pet and would provide a good home for yours. Cruelty aside, monetary gain appears to be the strongest motivation for these acts.