People who don't wear their jeans/pants long enough, dragging on the ground is bad enough, but it gives me the heebies seeing someone who is nicely dressed but needs another inch of material on their pants or an inch off their legs.
People who dye their black hair blonde and then not bothering to get the re-growth done. I remember years ago i dyed my blonde hair browny/red and had blonde regrowth, the hairdresser was peeing herself laughing.