I've serviced a few sets of (my own) Honda brakes that had the seized
'slider pins'. The most obvious symptom is when the pads wear out three
times as fast on one side of the rotor than the other. They are numbers
14& 16 on this (typical) diagram:

http://tinyurl.com/yss53w

When the pins seize you can use the bolt to fasten the frame part of the
caliper assembly to something immovable (like your trailer hitch) and
then you wiggle the frame back and forth while slowly extracting the pin
from it's hole.

Has anybody ever seen a 'puller' that's made specifically for getting
them apart?

'Curly'