Mr. Monk and the Big Game - S5-E3
Stupidity: It makes no sense for the murdered coach's brother to stick around since they were getting close to him much less attend the game.
Mr. Monk Gets a New Shrink - S5-E7
Stupidity: Merrigan should've removed the heroin from the statues once he got them, thus the whole murder of the cleaning lady and discovery of his drug dealings might not have been discovered.
Mr. Monk Can't See a Thing - S5-E4
Stupidity: In the beginning, Natalie walks into the firehouse, sees two people hurt, and instead of calling 911 EMS, she calls the captain, delaying the EMS services.
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.