Check their relevant licenses to see if they are valid. Yes, it may cost a little money - but you can't simply have complete stranger cleaning your home - smart? Keep in mind that the product range of service varies from company to company depending the skills of their workers. http://Ww17.lankanto.com/__media__/js/netsoltrademark.php?d=Www.Wakewiki.de%2Findex.php%3Ftitle%3DCleaning_Supplies_In_A_Cleaning_Business