Stop sites like used sandwell and gumtree from allowing people to give away animals for free

I believe that a animal should be sold not given away there are so many dangers to giving them away for free, like dog fighters look online for dogs, cats and rabbits to use as bait for other dogs to attack or the animal may end up being abused by the new owner.
I have read so many stories of people having dogs/cats free and either end up killing them through abuse and neglect or abandoning them, i read a story a few weeks ago actually about a man who seriously bead his staffie and then chucked him off a twelth floor balcony.
Please end the free to good home for the sake of these poor animals