Phil Allison wrote:

Please do not confuse Power Factor Correction (PFC) with power supply
efficiency. They are two separate items.

** OK so far.

Gee, thanks. [Red flag warning!!!]

PFC can be either active or passive,

** Hmmmm...

Careful, a hint of ignorance is showing.

but usually alters the highly capacitive input of SMPSs.

** TOTAL ******** !!!

They are not capacitive, there is no phase angle.

And it's finally out. He's a total loon.

There is a big 400vdc capacitor (or two 200vdc caps in series) just after
input rectifiers on the AC input. Note C5 and C6 on:

http://www.pavouk.org/hw/en_atxps.html

They charge to the peak value of the input
AC voltage, or 1.414 times the RMS value. Since the cap(s) draw their maximum
current when at lowest charge (zero cross-over point), and draw their least
amount of current when charged to their highest point, the current waveform
*leads* the voltage waveform by 90 degrees. [Maximum current is at the same
time as minimum voltage; minimum current is at the same time as maximum voltage.]