It was really sad to see how trash is all over the country no matter where you go. Dumpsters are extremely disgusting, full of trash left rotting for days in main streets. People throw away anything anywhere.
I've been to Djerba island and litter is even on beaches. I've seen litter floating in the water which deterred me from taking a swim. On one occasion I even spotted a half broken umbrella pole rusted and buried in the sand, just waiting for someone to be seriously injured which I obviously removed. Broken glass in beaches is also common, so be careful and always wear flip-flops.
This is a huge cultural and not so easy to solve problem as I've seen people dumping trash in front of me as if something completely natural. It is sad because if that problem is solved, it is actually a beautiful country.
Other countries suffering exactly the same problem that I've visited are Vietnam and Maldives.