While the raccoon looks like a friendly animal - they are NOT. Besides making a mess in your yard, they are carry of a number of diseases including rabies. They can be aggressive and will attack a dog if they feel threatened or if cornered. These encounters seldom go well for the dog.
Raccoons have adapted very well to the urban environment. While their natural diet is mainly insects, worms and native nuts and fruits, they readily feed from garbage cans and compost bins. Blessed with a natural curiosity and an intelligence that matches dogs and cats, most garbage cans and commercial compost bins do little to deter these garden raiders.
Even the common trick of putting a weight on the lid, which will keep out cats and dogs, will not deter the raccoon. The raccoon’s ability to stand on its rear legs while pushing with its front paws allow it to lift a considerable weight. In the video a raccoon can be seen lifting a compost bin lid enough for the 20 pound cement block to slide off.
Raccons travel in family and social groups. Once the group has found a food source they will return to it. While there isn't any evidence that adult raccoons learn from each other, a mother raccoon that has learned to open a compost bin will pass that knowledge on to her kittens.
The Speedibin was designed with animals like the raccoon in mind. The large lid that fits over the top of the bin has a two inch lip all the way around and a one inch tab at the back. To open the Speedibin, you need to twist the handle to un-latch it and then slide the lid off the back tab. As you can see from this picture of foot prints on this Speedibin, raccoons were not able to get in. The latching handle also keeps the lid on in high winds and keeps dogs out too!