Unfortunately, the pax look at your appearance, and judge you by it, regardless of your ability. If you look like a professional pilot, capable and experienced, they will beleive it. If you look shaggy and unkempt, they will not. Their first impression on how you look will be how you, and your employer will be judged.
Keep it conservative and present yourself as a professional. If you don't, do not expect to be treated as a professional.