Chunky, thick rubber soled shoes - women-think polished and sexy shoes; men-a party is a great reason to impress and go totally GQ
Casual shoes with your tux - guys, rent the black patent dress shoes!
Out of season shoes or totally out-of-style, over worn or dated shoes - hear Jimmy Choo calling you and go shopping!
Heavy cologne or perfume
Overdone makeup
Overdoing the jewelry or jewelry that clinks, jingles or makes noise.
Anything too insufficiently modest, slinky or sexy to mingle with your co-workers and/or boss - you have to see these people on Monday
Dirty Nails - women - go bare and buffed rather than chipped or worn polish; men - learn to use a nail file and moisturize hands and cuticles (you might start a new habit!)
Dirty or worn collars or cuffs
Anything stained, dirty or faded
Anything with tears, broken seams, thin spots, holes
Missing buttons, snaps or other missing decoration (beading unraveling or missing), broken zippers
Too casual, out of date or worn out hair accessories (think no shine left to the gold or silver clip or dulled with a coating of hair spray)
No straps, lines or bumps show through your dress-match your undergarments to your outfit
Too somber for a festive occasion
Something you can't sit down in comfortably
Any possibility of a wardrobe malfunction - think Janet Jackson