If you scrub your face with an exfoliant that's a bit too harsh, if brojen veins were to appear would this be seen mmediately or take weeks?

Scrub: Both are possible but broken veins are not usually the problem unless the area was really traumatized. There was a facial scrub that had apricot pit fragments in it. These little hard particles caused gouges on the skin and resulted in scarring. Be gentle on your face. Blackheads are not due to dirt. The brown color is oxidized lipid in the follicle.