This looks like just the app I need, something to delete all those .trashes and .ds files on my USB thumb drive so that when I mount the drive in windows, half the files are not junk. It says that it will scan a folder or volume, delete all those pesky files and then eject the drive.
When I launch the app and select my drive it gives me the option to select just a folder (the folder had 5 items, but FC reported deleting 40 .ds files), but it then looks like it deletes all the .ds and trashes file on the drive. When I click on eject nothing happens. The drive remains on my desktop. If I pull it out the system gives me an annoying warning not to do that, and when I mount the drive on my windows machine I see FinderCleaner has done absolutely nothing.