|Steve Edwards' website|
The strange custom of black-footwear-as-neat-dress appears to have been a vestige. When I left Ireland a few years later this practice seemed to be fading from importance.
All you need to know about getting in to an Irish nightclub is that you must wear "neat dress." In reality, that means black leather shoes. Truth is, it doesn't matter what else you're wearing. Casual footwear is unacceptable. No runners. You may be wearing some beat-up pair of German army boots (as I've done.) It doesn't matter. T-shirt? Ripped jeans? It doesn't seem to matter. You must wear black leather on your feet. And no baseball cap.
There's no sense to it, and no explanation is possible. There are few exceptions to this rule, and I have only evaded it a couple of times myself. [I've heard that this practice has fallen out of use in Dublin; however in Kilkenny it still pretty much holds, as far as I know.]
Clubs generally play very loud dance-type music. They can be crowded, and rather drunken. They are not at all like a pub, for conversation and a convivial pint.
But there's no alternative, after the pubs, if you want to drink in public.