Proper rain gutter installation is extremely important for the structural integrity of your walls, doors, windows and the foundation of your house. It is important to make sure that rain gutters are clean and do their job correctly in order to protect your home.
A major problem that can occur if your rain gutters are not tilted to the proper angle is that you will have standing water in your rain gutter. This will not deliver the water properly to the ground and away from your foundation where you want it. Also standing water will cause rust and erosion and damage your gutters.
It is important to make sure that your rain gutters are securely attached to their support structure. This support structure should provide the proper angle for the water to run out of the gutters.
The proper angle for your rain gutters is basically that angle that allows them to do their job properly. When installing rain gutters you can test this yourself by pouring water into your gutters. Any water poured in should run directly to the down spouts however your gutters should not be so angled that they hand down in an obvious way.