The term “apple polishing” is recent; the practice was known to your grandfathers and probably goes back to the Garden of Eden.
Undoubtedly the wily serpent saw to it that the apple of the tree of knowledge looked attractive before offering it to Eve.
The apple polisher of today is one who offers blandishments; one who, his father would have said, uses “soft soap,” or what his grandfather would have called “soft sawder.”
The term got its name from the long-time practice of the schoolboy, rarely schoolgirl, of carrying a beautiful and tasty, highly polished apple to school as a “gift” to his “well-beloved” teacher.
Of course, it was nothing but a bribe, hopefully offered to one whom he secretly considered a lantern-jawed harridan, with the silent prayer that she would overlook any peccadillos that day.