John,
You make good points, but I think you're being a little bit too black and
white about this. There _are_ effective EMI/RFI filters out there, but I
agree with you that pretty much anything that doesn't have real test results
with numbers is probably entirely hit or miss as to whether or not it's going
to do a lick of good. Additionally, what many people don't realize is that
most appliances have plenty of EMI/RFI filtering built-in, since it was needed
to pass CE or FCC certifications, so any provided in a power strip may be
redundant.
Meanwhile your logic is that if a fan in a printer or a car runs
after power off, then if fan does not run, damage will result.
Nonsense. Spin that only a politician could love. Does the laser
printer or car get hotter when powered off? Of course not. If a fan
does not spin, the laser printer and car still cool - just slower.
Although an unpowered device can't generate any new heat, what _can_ happen is
that the heat that's still present when the plug is pulled can distribute
itself differently than if the fan is allowed to run, and this can potentially
damage other components. An example would be something like a video
projector... with a fan going, the heat from the bulb is shunted away from any
run-of-the-mill components, but if the plug is pulled those components can end
up being exposed to temperatures well outside of their specified range.
Makes no difference whether power is removed by printer switch, power
strip, or wall switch.
As a practical matter for a single printer, I suspect you're correct, but I
also believe that statistically speaking you would end up with more product
failures using a wall or power strip switch. For big companies with hundreds
or thousands of printers floating around, this is significant.