I mean, if you reverse pickpocket better equipment onto NPCs, they don't equip it, at least not in any playthrough I've done.
With followers, if you give them equipment, they only wear it while they're following you. Tell them to get lost, and when you go back to get them again, they're in their normal clothing/armor.
And spouses, they still wear their default clothing after they're married, and there's no option to give them new clothing or to ask them to change their look like you can with the kids just by gifting them an outfit. Like say if I married Brelyna or Rayya, they both wear those ridiculous hoods all the time, or Rayya, Aela, and Mjoll, both never wash off their face paint. Or pretty much any spouse who wears casual clothing, like Ysolda or Sylgja, I might want to purchase a fine clothing from Radiant Raiment for them as a gift, but they would never wear it because of how the game is programmed.
Patch 2.0, when it eventually comes out, should amend this. Let us spoil and dress up our friends and spouses!
Inb4 "Use mods" I am a PS3 user, mods are out of my reach.