Fancy, "performance" headlight bulbs
Super-bright headlight replacements sound great in theory, and the problem isn't with the bulbs themselves but with the cars in which they're installed. If headlights aren't aimed properly, they can easily blind oncoming traffic, which is something almost everyone who's driven at night can understand.
Just as bad, and far more common, are headlight covers that are scuffed from years of debris getting kicked up along the road. Every one of those scuffs causes light to scatter, so rather than seeing further down the road with your new, brighter headlights, you're increasing the glare that creeps into the oncoming traffic's line of sight.