Definition of mere scratch:
(v) :
to
rub a surface with a sharp object, especially by a living creature to remove
itching with
nails,
claws, etc; to
rub the skin with
rough material causing a sensation of
irritation
"could you please scratch my back?"
"I can't believe there is a scratch in the paint already."
"this is scratch paper, so go ahead and scribble whatever you want on it."