Wow...so out of everything discussed in this thread (besides the black/navy thing...to which I'm in total agreement!) the only thing I will never wear is Crocs. I hate them. I hate them. I hate them.
My mother thinks they're great gardening shoes, so she bought two pair. One pink. One green...
lol. She claims she'll spray paint them for me.
Other taboo items:
Fake designer bags
Flannel
Patterned bottoms
Colored jeans (green, orange, red)
ETA: Shredded anything. Acid wash anything. Bleached anything. Tie-dyed anything. Oh, and extreme flare jeans- in my heart I do not believe they look good on anyone person over the age of 15.