You know, I mentioned that line in the Darkwing Duck "Twitching Channels" episode, and I must wonder... Could there have been a special reason for them asking if Launchpad always wore the same clothes? Because pretty much every regular character on the show had one regular outfit each (Darkwing had two, his Darkwing Duck outfit and his Drake Mallard clothing).
I guess it would have been one thing if Launchpad was always seen in his regular clothing, because it is common to see cartoon characters in other outfits besides their regular ones. But Launchpad was seen in other outfits, on both DuckTales and Darkwing Duck. On DuckTales he was often seen in his Junior Chipmunk scoutmaster uniform, in Launchpad's Civil War he wore a civil war outfit, in Hero for Hire he was seen in both superhero clothing and a robe, in Double-O-Duck he was disguised as a secret agent (and I think he wore multiple outfits in that episode). While on Darkwing Duck he dressed as Darkwing on a few occasions, I recall seeing him in swimming gear in one episode, wore a number of costumes in Hush, Hush, Sweet Chartalan, and wore a suit in Star-Crossed Circuits.
They could have easily asked if all characters wore the same outfit or if their clothes all looked the same.