Have you felt the glands to see if they feel fullish? Since he has a history of soft stool he may not be able to fully express them himself, though larger dogs tend to be less prone to anal gland issues than smaller dogs. They may not be full enough to be a real bother or irritating, but enough that he can feel them.
I also think some dogs do just tend to scoot a bit more.
Does he scratch his body more than 'average'? If so, maybe a touch of dry skin or something.
I also think some dogs do just tend to scoot a bit more.
Does he scratch his body more than 'average'? If so, maybe a touch of dry skin or something.