[Michael Romanos]

I would trim a fluffy Corgi's trousers or skirt a little if the volume of hair was interfering with their toileting ie often leaving traces of poop on that part of their coat.
However if a fluffy was to get an all-over trim to be more comfortable in the warmer months of the year, this would include the trousers or skirt (or pants as you might call it) to retain a more even appearance.