Determine the residue of the detergent or shampoo before applying it to the upholstery. Excess will remain in the upholstery fabric to attract and hold soil. Use a clean glass pie plate. Add approximately 1/4 inch of the detergent water mixture or shampoo mixture. Allow liquid to evaporate; to shorten time of evaporation, place pie dish in the sun or in an oven set no higher than 150 F. After all liquid has evaporated, examine the remains to see what is left in the pie plate. Has it dried to a powder which can be vacuumed. To determine whether the residue is sticky, oily, or waxy, run a finger over the inside of the plate, and rub the fingers together. If the residue is sticky it will hold onto soil at an accelerated rate and make the upholstery fabric soil faster.
Once the sticky or waxy residue gets on the fibers, it usually remains until the residue is flushed out with a lot of warm water. Another cleaning with the same solution will only build up the residue. If it is suspected that a residue is already present on the upholstery fabric, place a tablespoon of warm water on a spot and work it in with the fingers. A foam or a slippery feeling will indicate a detergent residue. The best way to remove it is by the hot water extraction method using clear water.