Dreampanther
We all face the reaper.
Depends on the character and the costume for me. Batman's outfit is functional, as he designed it to be dark and threatening - specifically to scare the sh!t out of bad guys creeping around in the night.
The Punisher and Lobo works for me too - Lobo has the biker thing going for him while the Punisher is usually in combat gear - he only added the skull so the bad guys would know who it was that ended them.
Superman comes from an alien planet where they wore weird-ass outfits anyway - what was in fashion there doesn't have to make sense here.
Chicks wearing skimpy outfits like Black Canary also works for me - Modesty Blaise called it The Nailer - she would take her top off before walking into a room - then, for the couple of seconds while the bad guys' eyes were nailed to her boobilicious chest, she'd be nailing them - right through the head.
In most cases I don't have a problem with a costume - except if they don't update them. The same way that we don't wear hippy outfits from the 60's or disco outfits from the 70's anymore, there is nothing wrong with updating costumes to reflect a more modern age - like that latex costume Silk Spectre wears in Watchmen...
Gulp, umm, speaking of which - I think I need to go and have a quick lie-down now... 😈