Not sure if this is really a bad idea...However, this would fall more under "restoration" than cleaning...Scraping down the grout lines is a "last resort" to what "cleaning" can't actually accomplish...This tool could come in handy on some jobs that have discoloration from hell...However...Any perforated edge works...Glad to see this guy can make a few bucks...I'm sure he'll be on Shark Tank here partnering with Mark Cuban...LOL