The annoying Monk was on display the moment he scowled at Natalie with the ladle. This seemed extreme even for Monk; was he going to throw out every utensil and appliance she used in the kitchen? Hasn't he already accepted at least her "cooties" when it comes to his stuff?
But annoying Monk -- germophobe to the nth degree -- was in full force, freaking out when his clients, homeless bums Ike, Reggie and the Professor, hired him to find out who killed their buddy, Willie. I know Monk's discomfort over their filth and lack of social graces is meant to be laugh-inducing, but it's a fine line between him being annoyed and him being rude. Natalie is the counterbalance, so you could count on her for the true Christmas spirit (and Julie, too). Although they didn't show how it got that way, the best gag was the way Monk wrapped his furniture wrapped in plastic and cordoned-off parts of the apartment.
The better half of the episode dealing with Leland's bad back and overwhelming sadness. Has it really been two years since his relationship with Linda ended? My heart was aching for him, which made his conversion at the monastery all the better. When Monk tried to talk to the monk who had taken a vow of silence, the "shush" bit was very funny -- reminiscent of Seth Green and Mike Meyers in Austin Powers -- even though I was waiting for a topper, a way for Monk to communicate without speaking. The charades when he finally found Leland was predictable.
Ultimately, of course, the truth about the fake waters of the fountain was revealed and Badalucco apprehended after his girlfriend confessed. Natalie and Monk sneaking in as monks and chanting the information to him was very funny, "Here's what happened." I liked the idea that Leland's faith was restored by the "miracle" recovery, but his cop instincts should have told him something was off about the fountain. As a character, he's not that naive, even with a bad back. Monk was suspicious from the start.
Other points of interest:
The chalk/herbal concoction that Stottlemeyer drank and Monk connected back to Willie's murder was a reach. He should have confirmed the connection by testing the bottle to see if the bottles were Leland's because of DNA. Otherwise, why couldn't the bottle have come from anywhere in San Francisco?
When talking to the pharmacist, Leland referred to Randy as his partner. Hmm.
Without the moustache, Leland looked younger. With the moustache, Randy looked funny.
In the final scene, did Monk drink from the fountain? I think not. He just cannot believe.
What was the joke about the bum's gravy? I still don't get it.
Leland's gift to Randy was a razor.