I think bowties are a must in black tie or white tie events. Nothing looks better with a tuxedo than a black bowtie. Most of the time, I think bowties look bad with a suit unless the wearer is trying to achieve a particular look. Bowties do not look bad in shirtsleeves if the wearer is seeking a daring, yet ironic geeky look. I see it in some settings and some young guys manage to pull it off.
I think one should always tie their bowtie and never wear a pre-tied or clip-on rig.