I have no Scripture to back my opinion here (gasp), but I think the best look a preacher should have is to be dressed appropriately for the occasion at hand.
Funeral - Dark suit and tie (Most families would view flip-flops as an insult to their dead loved one)
4th of July BBQ outing - No tie...or dress clothes. Flip-flops are appropriate here.
Visiting in the hospital - Should wear professional looking clothes (no tee-shirts, shorts, or denim). Volunteer clergy at our local hospital have to meet this basic requirement.
Church biking activity - shorts/tee shirt is fine.
Sunday morning service - Should dress like he is doing something important (if not a suit, at least something nice).
*I wear a suit, but some of my favorite preachers wear slacks and a simple collared shirt. That isn't a problem to me.
John the Baptist didn't dress like the clergy of his time for sure, but his ministry was a little different from the average preacher.
