Originally Posted by Manton
Suede shoes in summer, brown in town, mix four patterns, socks don't match trousers, mix metals, light shoes with dark suits. Among others.
I am guilty of the ones emphasized in Manton's post.
I should add the disturbing fact that I will pair jeans with just about anything. That means I can be spotted with a very formal attire, but with jeans (I am wearing today a FC shirt with metal vintage cufflinks, dress shoes, knee-length socks, but with jeans).