Dye bleeding occurs when a colored fiber loses dye while wet. Uncolored or light colored fiber or yarn may readily soak up fugitive (runaway) dyes from the darker fiber or yarn and become stained. This is most often seen in rugs and carpet where deeply dyed shades (for example: reds blues blacks) become fugitive and bleed into white or light colored areas.
At least two conditions cause dye bleeding in colored fibers and yarns.

The first is a defective dye or dyeing method. In such a case, the dye is either poorly selected or not properly handled during manufacture. The result is excess, unsecured, weak, and/or unstable dye. When a dye with poor stability or wash-fastness is used, it may bleed during or after the first few cleanings. Likewise when too much dye is used during manufacture, the excess adheres near the outside of the fiber where it may readily wash away. Such defects in dye or dyeing method, at the time of manufacture, produce a textile product, which is defective.

Unfortunately for the consumer, these defects are not visible at the time of purchase.

In the second condition, dye is affected by use. Sunlight, atmospheric fumes, common chemicals, animal/pet residues, etc., can weaken dyes over time. Once dyes are weakened they may run or bleed with cleaning.
If pre testing or experience does not indicate a potential dye-bleeding problem, the carpet cleaner should not be held liable for using what would otherwise be usual and customary cleaning procedures.