I suppose they mean for an occasion. If you wore a tux to a dinner with evry one else in a business suit you would probably be better of than the guy in jeans, but not much.

If they mean style, understated always wins out. I understand the rule for women is to dress up perfectly (jewelery etc.) and then take one thing off.

My rules were, blues and greys for business. Add neutrals for casual. Button down or long collar dress shirts in light blue or white and be very careful with ties (seek advice). Socks should match the shoes and nothing else. Shoes black or cordovan, never brown. Lace up for business, slip on for casual.

Most important, the shorter and heavier you are, the more careful you have to be.

(not gay)