Most of the time these dark black clouds on an LCD screen are simply dust and dirt that accumulates from gasses produced by the "backlight". To draw an exploded view with (this) text a flat panel screen is trim > screen > inverter (electronic circuitry gadget) and backlight fixture > a (usually flat white colored) backlight reflector that just looks like a big white cover of some sort > and the back cover usually has the input/output ports, speakers, cooling fans and the back panel has vents in it for air circulation.
The white cover looking thing is where the black clouds usually are. If you venture in to taking it apart, which I do not recommend and take absolutely ZERO responsibility if anyone reading my response here takes their TV apart and screws it up, you'll see that black dust/dirt/carbon-like residue is in the same exact spots on the backlight reflector as it is on your screen. You might also notice the same gunk on the back of the screen in the same spots you see the dark spotty clouds when it's on and operating.
It wipes off and cleans up with just simply water or alcohol and a soft cotton or microfiber rag.
The don'ts:
- DON'T use any kind of cleaner except water or rubbing alcohol. Don't use Windex, don't use clorox or some kind of cleaning/disinfecting wipe; nothing but water or alcohol.
- Don't use anything but a *SOFT* cotton rag or microfiber fabric. Paper towels are convenient but they are not soft they are abrasive. Use one of your Holy white socks and file it with the bin gods when you're done if you don't want to wash and wear it again. If you're not 100% sure it's cotton or microfiber don't use it.
Reason for the don'ts: Damage prevention.
