Mildly broken in, maybe. NEVER worn out shoes.
I just came from my favorite running shoes store. On the wall was a sign that said, "Proper fitting running shoes never need to be broken in!" Another sign says, "The proper fitting shoes are probably going to be the ugliest. Don't buy running shoes for the looks, buy them for the way they fit!"
Blisters = bad fitting shoes.
WDW= lots of walking.
I earlier said two pairs of quality shoes for everyone, but I forgot the very important advice to ALTERNATE between those two pairs of shoes! In truth, it a pain to pack, but sometimes I even bring three pairs of shoes for longer trips. Well worth the packing space.
One of the best things I ever discovered was a runner's shoe store, not big box, not the mall sneaker store- the place where actual runners shop for shoes! A good advisor/sales rep examines the way you walk before they pull out any shoes for you. They'll also advise the proper size for you; not ask you what size you want.
Moleskin is inexpensive and very helpful for blisters. Inexpensive gel soles/heel pads can also be helpful (Payless Shoes for cheap ones)I rarely need it, but, well....sore feet= no rides. Cheap, and well worth a few $.
pair 1- sneakers
pair 2- quality, water tolerant sandals, ideally with adjustable straps- your feet swell over the day. This is why sneakers are also good. I personally prefer black, because they double as slightly dressier for ADR's. (My current favorites are Ecco brand- with multiple adjustable straps. Keens/Teva are also great and less $.)
Pair 3- comfy slip-ons just for the room, OR water park water shoes