Insects can breed there
Insects love the wet conditions of dirty and unkept gutters. If you aren’t taking regular care of your gutters, they will fill with water, leaves, sticks, dirt and other debris.
Disease can breed there
There are many diseases and illnesses that are associated with stagnant water.
Water damage inside your home
Gutters are designed to protect your home inside and out from water damage. If you aren’t paying attention to gutter cleaning then water can backup, damage your roof, and leak into your home