Stain

Chibi-Robo cleaning up a stain using the toothbrush.

A Stain is a mess left by the various members of the Sanderson family that Chibi-Robo can clean up using the Toothbrush or Squirter Chibi-Tools. When a certain amount of stains has been cleaned up, a Cleaning Bonus is given to Chibi-Robo by Telly Vision. There are several types of stains.

Bird droppings

Rewards 5 Happy Points. Found in Backyard, Basement

Mud

Rewards 2 Happy Points. Found in Backyard, Basement, Living Room

Paw print

A Pawprint is a paw shaped stain of mud on the floor. These stains were caused by Tao tracking mud into the house. Cleaning it up gives Chibi-Robo 2 Happy Points. Found in Foyer, Kitchen, Living Room

Scribble

A Scribble is a stain accidentally drawn on the floor by Jenny Sanderson. They can be found on the floor in the Living Room near where Jenny normally sits and draws, and throughout Jenny's Room. Cleaning it up gives Chibi-Robo 4 Happy Points. When Chibi-Robo cleans it up near Jenny, she gives Chibi-Robo 10 Happy Points and 10 Moolah. Found in Jenny's Room, Living Room

Shoe print

There are also Shoeprints left throughout the house, primarily around doors leading outside. These are left by Mr. Sanderson. Rewards 4 Happy Points. Found in Backyard, Foyer, Living Room

Tire Tracks

Rewards 4 Happy Points. Found in Foyer

Liquids

Main article: Squirter

Funky Sweat

This Is treated the same as water. It Rewards 2 Happy Points. Found in Bedroom

Honey

Rewards 2 Happy Points. Found in Kitchen

Oil

Oil takes longer than most stains to clean up. It often indicates a Spydor attack. Oil can be found in the Basement, under the Hot Rod in the Foyer, and above the fan in the Kitchen. When cleaned up, Chibi-Robo receives 2 Happy Points. It can be sucked up using the Squirter Chibi-Tool. Getting rid of the oil this way will not drain Chibi's Watts as much and takes less time, but it will not yield Happy Points or Moolah, but if Chibi sprays the oil on a Utilibot, they will give him 10 Happy Points. Found in Backyard, Basement, Foyer, Kitchen

Water

Rewards 2 Happy Points. Found in Backyard, Basement, Chibi-House, Kitchen, Jenny's Room, Living Room, anywhere Telly cries

Cleaning Bonus

After Chibi-Robo cleans his first 10 stains, Telly Vision will give him a Cleaning Bonus, awarding Chibi with Happy Points and Moolah. After this first Cleaning Bonus, there is a 1/31 (or 3.23%) chance that a Bonus will be awarded every time a stain is cleaned. The amount of Happy Points and Moolah awarded is determined by Chibi's "level", which is how many battery upgrades Chibi has, with level 0 being no battery upgrades.
The formula for how many Happy Points are awarded:
(level + 1) * 5 + random number between 0 and 5
The formula for how much Moolah is awarded:
levels 0-1: (level + 1) * 20 + random number between 0 and 10
levels 2+: (level + 1) * 20 + random number between 0 and 20
Therefore when Chibi has infinite battery (level 14), he will be awarded somewhere between 75 and 80 Happy Points and 300 to 320 Moolah.