xxx.xx mb junks found!
Recommend to clean
I got the message above recently on my phone. A brief search shows the offending app is ES File Explorer. It seems I and anyone seeing this message with the ability to use a search engine is now uninstalling ES File Explorer.
https://www.reddit.com/r/Nexus5/comments/3tpwji/sothis_totally_legit_looking_message_popped_up_on/
http://forums.androidcentral.com/android-6-0-marshmallow/611585-201-34-mb-junks-found-recommend-clean.html