Leather garments are made of skins taken from various portions of an animal and usually from several different animals. The manufacturer tries to match the skins so that your garment is as uniform as possible, but even with the best matching, there will be some variance in texture, weight, and colour uniformity. These variations may be accentuated after cleaning. 

Loss of Colour – 
Be prepared to see a slight variance in the depth of colour after cleaning. In the manufacturing process, the tanner immersed the skin in a dye bath to obtain a uniform colour, but skins from various parts of an animal may vary in colour fastness. The cleaner can correct some colour variance, but must rely on spray dyeing, which will not dye the leather or suede to the same degree as the original immersion process. 

Loss of Oils – 
During tanning, leathers are impregnated with oils to keep them supple. Some of these oils are lost in cleaning, and although the professional leather cleaner has special additives to restore suppleness, there could be some change in the feel of the garment.