Remember in "Aliens," when the doomed crew of space marines realizes that the xenomorphs bearing down on their position are actually solving problems and learning through observation? Apply that same logic to raccoons, because while they may not bleed acid, they adapt very quickly to their surroundings.
For example, Germany is so overrun that they placed mounts over their drainpipes so raccoons couldn't climb their homes and destroy their rooftops. The crafty critters figured out ways around the mounts and still got up. Some researchers think that by creating more obstacles for them, we may actually be helping raccoons get smarter. In fact, many compare the evolution of humans to raccoons because we both learn in a quest for food. Like us, raccoons are omnivorous and get fairly creative about what they'll eat.
This is especially true of raccoons in cities, where they've adapted exceptionally well. Their capacity for learning is so individualized that scientists have found studying just one set of raccoons doesn't yield data that's indicative of the general population's behavior. In the PBS documentary "Raccoon Nation," researchers discovered that the raccoon territories in Toronto were fairly small, only 3-4 blocks wide. They also learned that city raccoons live longer than their rural cousins, probably because their only urban predator is the automobile. They're so smart that Toronto's raccoons actually build their territory around major roads to avoid cars.