That advice is kind of wild when you think about it. It's not really about the clothes, it's about being forced out of your comfort zone to see things differently. Makes you wonder what other creative blocks could be solved by just changing your physical surroundings for a bit. The best ideas often come from places you'd never normally look.
Watched my friend stare at a blank canvas for weeks. Told her to just go sit in a laundromat for an hour, like you said @sarah829. She came back with this wild painting of all the different socks she saw tumbling around. Completely broke her block.