That method works pretty well. Everybody on a parks maintenance crew that I worked with in college kept a bottle of clear polish in their lunch box. I just prefer not to get them to begin with, I spray down with some type of Deet based repellent if I am heading into chigger habitat.
Had my 3rd round of the chiggers this year. Tired of all the itching! So I Found a remedy, by dabbing a little of the Barracudas Nail polish on each spot. Stopped all the itching in about 10 minutes. Has anyone every tried this? Or any other treatment to get rid of them?