Why lightmap so dirty on Mobile (Android Test)?

Hello guys, I need your help. I can´t find a solution for the problem of the stains and dirty lights in mobile devices (Android, tested in a Sony Z3). I checked [here][1] the answers and questions but this is not a solution man.
I need to use white walls or clean colorful walls in my project…and I have to use a texture as solution?. I tried to use a texture with minimun details of a wall paint, and the result is the same.

Thanks for your help!!

Here are some screenshots of the mobile device.