There are some municipalities where landowners are required to remove graffiti in a timely fashion or be fined by the city. In such places, the landlord would definitely pass those costs to tenants. Not that they would lower rents if the problem went away, of course. One year of a graffiti problem would likely permanently raise rents unless you live somewhere with a glut of available affordable rentals.
The red mirage/blue shift will probably be much smaller than prior elections, since it seems Trump supporters are using early or mail in voting more than before. The splits by party for these methods are smaller so far this year.