I receive at least one call a week from frustrated homeowners, house flippers or investors asking me to re-pitch poorly installed gutters. Their thought is that it will be a cheap and cost effective way to make improperly installed gutters function well.
They are mistaken.
Gutters have a piece of flashing that is shaped like a hyper-extended letter L. One flap goes under the shingles (or metal if you have a metal roof) and the other hangs down along the fascia board. The gutter then comes underneath that flap that is hanging down (along the fascia) and that allows water to sheet off of the roof and into the gutter without damaging the fascia board.
Then, (most) gutters are attached by hangers that hook into the front of todays modern k-style gutters and are attached in through the back of the apron and the gutter. The installer then secures it with either screws or nails which go through and connect the back of the hanger, the hanging part of the gutter apron and the back of the gutter, into the fascia.
When a handyman or otherwise unskilled installer tells you they can repitch a gutter, they will be moving the gutter down (remember that the apron cannot be moved down with it), and then an additional hole pierces through the back of the apron and into a part of the gutter that cannot be seen due to the flashing hiding it.
That now-hidden hole allows water to get behind the gutter and rot out the fascia.
While this is a solid construction rule of thumb, with only one exceptions. If you live in a dry climate with low annual rainfalls which does not have freezing temperatures that will allow ice and water to build up behind the apron, this rule is less important.
However, if you are considering buying a house where the gutters have been repitched, you should keep in mind that if they would hide such a glaring problem by making the problem worse, what else are they hiding?