Urinals are the one fixture in plumbing history flushed the least.
One of the hottest topics in commercial construction is whether to flush or not flush when it comes to urinals. Waterless and waterfree urinals are the buzz in the plumbing engineer's office. There is an ongoing debate about the viability of using a urinal that does not flush water. The discussion centers on odor, sanitation and maintenance.
Every male, at some point in his life, has used a nonwater-supplied urinal. We have either called it the woods, an outhouse or a port-a-potty. The one similarity to all of these makeshift urinals is the odor associated with their use. Hence, we tend to have a bias that urine is going to stink.