So, i found this thread interesting.
I had not the same scenario, but very similar to this one.
So, my wife had a phone LG L Bello.
Lets say its decent phone.
Few days ago she got brand new LG Spirit from her father.
So she gave Bello to our older son and took Spirit for herself.
My son is 6 years old, going to 1st class and phones, tablets, notebooks are very interesting to him.
He loaded it with many games in just two days (mostly Minecraft) he is crazy for it.
But today he told me he is having some strange issues with that phone.
Getting some nude images, word sex and adult advertisements.
So I took it to check.
I noticed 10-ish strange apps are installed.
Please look at the pictures
Tried to uninstall them, but they cannot be uninstalled as regular apps.
They are not in the list of the apps at all.
I checked android administrator apps and they were not there.
So I got idea to reset the phone to factory settings and get rid of it.
Done it and I was happy with it for about 5-6sec then I saw this
So, a question for android experts.
How they (apps) could survive factory reset?
And start wakening as phone starts to boot for first time after reset.
I changed gmail password to get protected (read it up in some post).
Done reset 2-3 times againd and the same thing was happening again every time.
So I rooted it, put Titanium Backup on it and found the apps.
Uninstalled them and the problems gone.
Thia ia very strange, isnt it?