After discovering adware in a new version of ES File Explorer, Android users compiled a list of apps that sneak in an adware-infused charging lock screen and have found there are already about 20 of them. These apps violate the Google developer policy and should thus not be available via the Play Store.
The spreadsheet includes apps like ES, Xender, Z Camera, FotoRus, and more. None of these apps tell you upfront they will slap ads on your phone while it's charging, but they do. I checked a few of them to make sure, and it's the exact same screen we saw on ES (an extra lock screen for charging that has ads on it). It's not opt-in, either. The "feature" activates itself. It's a stripped down version of DU Battery Saver, an app that has over 10 million (obviously paid) reviews on the Play Store. And let's be clear, this app does absolutely nothing good for your phone. It's garbage, and now the developers are sticking their garbage in other apps.