Since many of the homes I buy are older I want to determine if it is a grounded system, if there is knob and tube wiring or newer romex, etc.

Perhaps I will make a video and use it to build a buyer's list, use youtube, tube mogul, sell point?

No umelot here Uwe, 1930 was wire and tube, not good, but that's probably what was meant too by the update.

At 36K feet bouncing around in a tube in sever turbulence makes for a gut wrenching few hours.

Paint chipping, Water heater tube missing, mold etc.

For example Google: as they grew they began to by other money generating firms like You Tube, DoubleClick and most recently EBook.

We put glass block in to repalce the old ones and even the advanced glue type block windows mold.If you want a window to vent the room, get a bath fan.If you want a window for natural light, get a skylight or a solar tube.

Bryan,If you get a call of a leak and the tub needs to be caulked it can take 30 minutes to get there and see what the problem is. 1 hour waiting at the pro desk to be caulk remover and a tube of 1HR caulk ($15) and driving back to the job. 10 minutes of prep and 5 minutes to caulk.

But the bigger danger is something serious like child porn. 

The water goes up to about a half inch below the fill line on the overflow tube.