The front trough motivates water to go straight into the gutter rather than dripping over the side. Other micro-mesh gutter guards that do not have a trough and are flat tend to have water go straight over the gutter, causing dripping and unsightly staining on the side of your gutter. As for debris collecting on top of the gutter guard, with a combination of the wind and the rain, most of the debris typically just blows and washes right off our gutter guard. However, all gutter guards have to be maintained periodically. Most people blow or brush any remaining debris off of the gutter guard.