Mr. Monk and the T.V. Star - S2-E12
Continuity mistake: The blood stains on Brad Terry's sweatshirt change positions after he runs back into the house. A few shots later, they're suddenly so faint they're barely visible at all anymore. Blood stains don't fade, at least not in just a few minutes.
Answer: Notice also that in the opening credits scene when he is touching parking meters her also wipes his hand on his clothes each time he does it.