This happens because residues are being left in the carpet which attract dirt. Usually this is caused by the use of soap in the cleaning process, when it is not rinsed out completely. Our professional carpet cleaning process leaves little to no residue behind to attract dirt, avoiding this issue.
It depends on the specific upholstery fabric being cleaned, but typical furniture/upholstery dry time ranges from 6-12 hours.
For answers to other furniture and carpet care questions, please contact us and we'll assist you.