Pro tip for LG G2.
The G2's camera lens is Sapphire glass, having a value of 9.0 on Moh's scale, i.e it can't be scratched unless you rub it with Diamond. But it is covered with a violet colored polarizing coating which is very scratch prone. Mine got scratched so badly that it started to make the pictures hazy. If your phone is suffering from similar issue follow the steps below.
1. Buy a tube of non gel toothpaste with salt. Best is the cheap colgate stuff. I used colgate visible white.
2. Buy some cotton swabs.
3. Put some toothpaste on the swab and vigorously rub the lens. Near the center is better.
4. The filter should start giving away within minutes. Keep rubbing it very hard.
5. Within a few minutes the center of the lens will be clean and again it will take great haze free snaps, the likes of which sets G2 apart from most other camera phones even today.
Metal polish works too but its liquid to chance to seep into phone.