I live in Oregon and have 5 hens in an urban setting. I have neighbors 20ft away from my coop so I am very conscience of keeping our chicken area from getting stinky. An unattended run will get smelly when wet in our weather. I had dirt and an uncovered run and within a month of our rainy spring weather this last year after getting our chicks and quickly found myself putting down several inches of sand mixed with Sweet PDZ, and adding a roof to our run. The sand helps emensly with drainage in our wet weather. The PDZ helps dry poop up quickly, thus eliminating a lot of stink. I use a kitty litter scoop to remove poop every day or so, which takes me 5 min because my area is small. There are certainly things you can do to reduce smell, with a little research, good planning, and effort on your part to clean up after the hens you can have a pretty sanitary coop and run. If you are able to free range them part of the time that will help even more.