In my experience, dishes are nothing more than garbage from the previous tenant. Furthermore, marketing your property on the rental listings as "satellite ready" isn't going to spur more positive attention either.
Get rid of the dishes and increase the drive-by curb appeal of the house. Make the future tenant go through the headache of taking care of the satellite dishes.
Make sure you patch up any screw holes with wet-patch when you remove the dishes though (if installed on the roof)!