Often a home inspector will call the gutters as overflowing and clogged, based on their outward appearance. When you pay someone to go up and clean "out" the gutters, make sure they also clean the gutters themselves, while they are up there.
Besides giving your home that extra sparkling curb appeal, dirty gutters are a sign that there is a problem. So when you get the problem fixed, remove the affects of that problem too.
How many home sellers get mad at the inspector for being "wrong"? If you have a 3 story house, often the inspector won't be climbing up to check those gutters. So get them nice and white, after you resolve the problem that is causing them to overflow for the length of the gutter.