Ask the cleaning company if they are vacuum before starting the cleaning process. There is a big difference in the results of work depending on this factor. If they tell you that they don't, you have to call other people. You want work done as efficiently as possible. Make sure to always suck the carpet dust before using the machine to clean your carpet. You can finally solve the machine if not, cost a little money. Make sure you are vacuum before the professional carpet cleaner works in your home too.