Jeff Liebermann wrote:
On Tue, 16 Oct 2012 00:39:42 +0000 (UTC), gregz
wrote:

Seems water soluble. They come off by scraping, or crushes into dust. I
don't see this anywhere else.
http://zekfrivolous.com/spots/page_01.htm
Greg

[Begin Sherlock Holmes mode]

Since your removal methods did not affect the underlying plastic, and
since plastic is not water soluble, I'll assume that it's not
something originating from inside the plastic. I'll also assume that
there was no spots on the front of the TV, or you would have mentioned
and photographed it.

Mold growth tends to be flat, while your spots have considerable
depth. The irregular shape and consistent color eliminates food
splatter. The lack of any deposits on the metal mounting bracket
indicate that it wasn't delivered by any airborne means (such as
plaster, Fix-all, cooking flour, ceiling tile patch, etc). The
partial photo of the bracket suggests that it's a wall mount bracket.
I would normally guess(tm) a spider infestation, but spider droppings
are usually black or brown, not white. The also land on horizontal
surfaces, not vertical.

So, what likes to stick to vertical plastic surfaces, doesn't stick to
painted metal, is white, powdery, and has to be scraped off. Bingo.
Packing material. The TV was probably stuffed back into its shipping
box without the usual plastic bag. While styrofoam is not water
soluble, some of the recycled paper fake peanuts can be cleaned off.
Same with the packing made from pop corn, soy, agricultural waste. To
sterilize it, the stuff is sometimes bleached. The metal mounting
bracket was added later, which explains why there's no packing
material stuck to it. The person that installed the TV on the wall
cleaned the visible front of the TV, but left the back a mess.
Humidity cycling eventually hardened the packing material. Nobody
noticed until the TV was removed from the wall.

"When you eliminate all other possibilities, what remains, no matter
how improbable, is the answer." (Sherlock Holmes).

Incidentally, I have a rather nice Olympus microscope in the office
that I occasionally use for such computer forensics.

Brilliant investigation. The stuff was not there when installed a year ago.
I don't currently have a microscope, but I'll try to get whatever
magnification I can come up with. The stuff sticks pretty well. I would
hate to look inside.

Greg