what is the aside on ActIII Scene 1 mean?

Polonius is telling Ophelia to put on an act for Hamlet to hide her true intentions for the "random" meeting. Claudius finds this personal as he makes an art of hiding his true intentions from everybody. He uses the metaphor of how the prostitutes make up cannot hide what she really is,

Aside: Oh, ’tis too true!
How smart a lash that speech doth give my conscience!
The harlot’s cheek, beautied with plastering art,
Is not more ugly to the thing that helps it
Than is my deed to my most painted word.
O heavy burden!

NO