Here is a simple solution for you to solve the “Stuck at 99%” issue.
How to Fix “Stuck at 99%” Bug
Sometimes after cleaning seemingly everything in a level you’ll find yourself stuck with a tiny amount of dirt left even after searching the entire map Fortunately there is an easy way to solve this.
Highlight messes by pressing tab.
This will make anything that needs to be cleaned show up in a bright yellow color. Dirt can be difficult to see when highlighted on some maps with bright yellow walls like the shoe house so pay attention.
Check the details tab.
The details tab shows you a list of every part in the map and the percentage of how clean they are.
To see this list, press escape and click details.
Try using different nozzles and extensions.
Sometimes you already know what object needs to be cleaned, but upon closer inspection it seems to be entirely clean. (Make sure you have checked every surface of the object, there might be something you didn’t see.)
Sometimes when looking for dirt at weird angles, the long extension can be useful (e.g. looking under a car at the wheels).
Alternatively, if there is some dirt wedged in a tight spot and it’s not coming out, you can spray and pray with the turbo nozzle. The turbo nozzle will shoot water at a high pressure, but spin quickly to help you reach some of these spots.
Lastly, the soap nozzle will clean most objects quickly and with ease at the expense of using up soap. This nozzle has a very wide range and will clean things like rust very quickly as long as you have soap and use the right kind.
The correct type of soap to use can be seen in the upper left corner.
The vintage car tires are just difficult to clean.
Plain and simply, there is dirt on these tires that seems impossible to clean. It can, however be done with enough patience.
My suggestion is to try using the soap or turbo nozzles, but I really don’t know if there is an easy way to get this spot clean.