Why am I not finding any outfits on the dream islands I visit?

Am I missing something? I even got the dragonite doll because I saw someone say that island has more collectibles (if you haven’t tried it- it really does!!) anyway, I’m trying to get a couple specific outfits for my ditto. I haven’t found not one outfit on any island. Am I doing something wrong? I’d also appreciate any tips you have about getting the most out of dream islands. I’m worried that I’m not actually exploring the whole island, or that there’s secret places I don’t know about. Any advice appreciated. Thanks!