That's a great and surprisingly practical question! The "best" color truly depends on your primary goal, as hiding dirt and being highly visible are often at odds. However, a smart compromise exists.
For hiding dirt, darker, earthy tones are champions. Colors like dark brown, forest green, or charcoal gray are excellent at camouflaging dust, pollen, and general grime. They blend with outdoor environments and don't show stains as readily as lighter shades.
For high visibility (important for safety near driveways or for collection crews), bright colors win. Bright yellow, lime green, or orange are unmistakable. They prevent accidental bumps and ensure the bin is easily seen for pickup.
So, what's the ideal balance? Many experts and homeowners find that dark green or slate gray offers the best of both worlds. These colors are subdued enough to hide a fair amount of dirt while still being distinct enough against common backgrounds like lawns, siding, or pavement to be located easily. They are practical and aesthetically pleasing.
Ultimately, consider your specific setting. A dark bin against a dark house may be too hidden, while a bright one in a sunny garden might be an eyesore. A dark base color with bright, reflective stickers or a brightly colored lid can also be a perfect functional solution. Choose what prioritizes your needs for cleanliness, safety, and curb appeal.