How many times has it happened, people? The do-it-yourself-er watches the 13-year-old YouTuber snip her own bangs, tries her hand at her own bang trim and winds up looking as if a starving weasel has chewed off her fringe. Another believes that those sunny, buttery highlights depicted on the box of color she bought at CVS are actually possible to achieve in her bathroom. In one afternoon. ON HER LEVEL 2 HAIR!

On the one hand, misguided home hair mavens provide you with a steady stream of new clients, who, if tended to properly, end up being long-term,…