I worked housekeeping at a college student residence with over 300 students (8 buildings for reference) for a period of time before I got into my current position in the office. Of all the cleaning products we had, Dawn Dish Soap was the most versatile. You really need the original blue Dawn Dish Soap, because it is the most effective. We would fill a bucket with hot water and a few squirts of Dawn and wash down walls with marks, dirt, grease, handprints and it would come clean with no effort. We would line dirty grout in shower floors and leave it to soak for an hour and those marks would come up no problem. It also took care of soap scum on shower walls. It really is a wonder product and we would use it over most of the expensive products we were ordered most of the time because it worked better!