That's a great question, and it's one that city planners and public works departments think about a lot. The short answer is: incredibly resistant, but not entirely invincible. Modern urban trash cans are specifically designed to combat graffiti, making cleanup far easier and more cost-effective.
Most high-quality public bins now feature specialized anti-graffiti finishes. The most common is a tough, non-porous powder-coat or epoxy paint. This creates a very smooth, sealed surface where spray paint and markers can't easily penetrate or adhere. Think of it like a non-stick pan for graffiti. When vandalism occurs, a strong solvent or pressure washer can usually strip the paint away without damaging the underlying finish.
Another popular solution is the use of sacrificial coatings or clear films. These are transparent layers applied over the bin's standard color. If the bin gets tagged, you don't scrub the graffiti off the metal itself; you remove the top film layer, taking the graffiti with it, and then apply a new protective sheet. It's a very efficient system for high-target areas.
The material choice also plays a key role. Stainless steel, especially in a brushed or satin finish, is notoriously difficult for graffiti to stick to permanently, and it cleans up remarkably well. The design itself can be a deterrent—complex curves, ridges, or perforated patterns make applying legible tags much harder.
So, while a determined vandal with the right tools can still mark them, today's urban bins are far from a blank canvas. Their finishes are a silent, active defense, significantly reducing maintenance time and costs, and helping our public spaces stay cleaner for longer. The goal isn't always to be 100% unmarkable, but to be 100% easy to restore.