Here is the solution to Gabriel Knight 3's first major puzzle, in which you must rent a motorcycle.  I've pulled it almost entirely from Gamespot, and have commented on it only when I could no longer help myself.

Since this next part where I quote directly from the Gamespot Gameguide is pretty dry, feel free to imagine that it's being spoken by OMM's new Adventure Gaming Mascot, Francis the Talking France:

Gabriel must disguise himself to fool the moped clerk.

You must combine several items to construct an adequate disguise and gain access to the motorbike. First, return to the museum and swipe the red cap from the lost-and-found box. You couldn't do this in the previous time blocks, but Gabriel knows he needs it now and has little trouble stealing the hat from the box. With the red hat in hand, head to the church.

Look at the Abbe's house and notice him watering his plants with a spray bottle. Wait for the Abbe to move back into his house and grab the spray bottle...   When you emerge on the new street, you'll spot a black cat in the corner. Move Gabriel up to the cat and use the verb menu to examine and pet the cat.

The cat dashes into a small opening into an old shed.  Examine the hole that the cat entered. Open up your inventory and pick up the piece of masking tape (if you failed to get the tape from Gabriel's hotel room, return there and open the dresser to get the masking tape). Use the masking tape on the shed door hole.

Walk back from the shed and notice the cat is now on a ledge. You can attempt to pet or grab the cat, but Gabriel can't because the feline is just too high. Here's where the spray bottle comes in. Select your inventory and pick up the spray bottle. Use the spray bottle on the cat, and he'll leap down and run, again, through the small opening into the shed. When he runs through the hole, he left some hair on the piece of masking tape you placed on the hole. Pick up the masking tape, and you'll gain black fur in your inventory.

Return to the hotel now and collect any items you missed the first time around that are vital to the disguise. These include the black marker from the hotel desk (just make sure Jean is wandering around), a piece of candy from the table near the lounge, and a packet of syrup from the dining room.

Head upstairs and knock on Mosely's door (room 33). He'll let you inside. If you want a hint about what to do with the candy, you can offer Mosely the candy, which he'll gladly take and consume quickly. Also, talk with Mosely about his passport, the key to solving the disguise puzzle. If you give Mosely the piece of candy, you must return downstairs and grab another one.

Locate the painting over the table depicting the street scene. Use the piece of candy from your inventory and place it on the table. Head down either staircase into the lobby. Look to the left of Jean's front desk and spot the room buzzers. Examine the buzzers and press the one for room 33, Mosely's room. This will buzz Mosely down to the front desk, but he'll become sidetracked by that yummy piece of candy you left for him.

This sequence could take a few tries to get everything right, but you can repeat the process as many times as necessary to secure the necessary items: the passport and gold coat. Just use more candy and keep pressing that buzzer.

Open your inventory now; make sure you have the black marker and syrup. Grab the black marker and use it on Mosely's passport to make a mustache. Next, grab the black fur from the cat and use it on the syrup to make a black mustache. Finally, use the red hat on the mustache and then on the gold coat to complete your Mosely disguise.

With your disguise ready, return to the moped rental shop.

My Adventure Game Credentials

In case anyone accuses me of simply "not getting" adventure games, I want to go on record as saying that I used to love this type of entertainment.  I played all the Infocom titles and even the Scott Adams adventures. I also used to enjoy this toddler busy box:

Regardless of how I feel about them now, I was the orginal adventure lover. For those of you who don't remember the eighties, I was pretty famous for my love of adventure.  I was a founding member of the Marlboro Adventure Team.

My entire wardrobe consisted of five matching Gymboree Aspen Adventure Swing Top and Beret suits.

The only philosophies I accepted were those of Age of Adventure thinkers such as Erasmus and Kepler.

I would only put food in my mouth if it was balanced on Oneida Gay Adventure Flatware.

Junior High bullies would ask me why I'd only eat off of Gay Adventure forks and teaspoons, and I'd say because I love adventure games, and then I'd get beaten.  After I discovered that I could tell them it was because I was gay, the beatings continued but were less severe.

During the height of adventure-game-mania, Fisher Price made a line of dolls based on real people who's super power was liking adventure games a lot.   Here's mine:

It was taken off the market after Fisher Price learned that I wasn't a stunt driving cowboy like I'd told them in the note I attached to a picture I found of the Village People riding in a dune buggy, but just a fat kid who's only claim to fame was that I was the youngest person ever to get such a bad hemorrhoid.

Later, I took the ultimate step towards expressing my love of Adventures.  I wrote about the experience under a pseudonym:

There was a second printing:

Eventually, I programmed my own adventure, the "How Do You Spell 'Adventure'" Adventure:

Most critics and players thought maybe it would have been a lot more challenging if I had misspelled 'adventure' in the title.  As a rebuttal, I took out full page ads in game magazines and New York newspapers in which I pointed out that maybe they could "go fuck their fucking selves".  In retrospect, they may have had a point.  I never worked in the game industry again.