Socks, one of the most mismatched things to wear I'm sure it happens to everyone. And you're right, if you don't take off your shoes, no one will know.
Anyways, I usually do well in avoiding such mix-ups, but there's one incident that comes to mind.
I was getting ready for a christening, and at the last minute, I grabbed a pair of earrings, putting them on while heading out. Everything went smoothly at the church, and later, as we gathered to celebrate with music and food, I decided to take a few pictures with my phone. That's when I realised I had been wearing two different earrings the entire time, both were hoop earrings, so it didn't look too bad, and there was the reason for the my mix-up.
I know this lady (whom I haven't seen in a long time now) One day, she went to work wearing two different shoes, completely unaware until a colleague pointed it out. The whole office had a good laugh about it. she even got a present from her secret Santa ,it was a pair of mismatched shoes. She even showed them to me