To the unbelievably vast rest of the world, yes they are. He will come off like a complete buffoon and set the opinion of the US back even more than…well, not trump but at least Budweiser.
Where do you get that impression? I’m not saying it’s not true, but why do you think that?
Budweiser is enormously popular in Ireland. “Icy cold Budweiser” taps in pretty much every bar or pub we went into - Belfast, (London)Derry, Galway, Dublin. Generally Bud, Guinness, and some sort of cider were the options. Very disappointing, especially given the quality and selection of beers and ales we found in even the most remote pubs in England, Wales, and Scotland.
I love my ukilts. Got my first in 2001, been wearing them casually since. (I fall into the “they’re comfortable” and “I like to be seen as eccentric” categories, as well as “I want to normalize kilts;” my gender expression issues are more clearly addressed by cute sundresses.)
That said, I’d probably never wear one in Scotland or Ireland for fear of being thought a wanker. No need to fuel any already-far-too-justifiable anti-Americanism.
.
. . . in about the 1890s, but the fad didn’t last.
The vestigial remnant of the fad is the the Irish army has a pipe band whose dress uniform involves saffron-coloured kilts. But that is the only kilt I have ever seen worn in Ireland, other than tartan kilts worn by people seeking to express a Scottish, not Irish, identity.
Just as a datapoint, I consider them clothes, not costume. They’re still just as much a “look at me” outfit as, say, a full-on leather-and-safety-pins punk outfit, asapeur suitorthose Japanese penis-pocket pants, but they’re definitely clothes, not costume - in a way tartan ones (mostly) aren’t, anymore.
Personally, I’d smile quietly to myself if some tourist (or local) was wandering round Cape Town in them, but I wouldn’t consider it an American folly. Just universal weirdness, and that’s cool. They’re pretty big with the Rennfaire crowd.
(I think Rennfaire is also regarded as a characteristically American eccentricity.)
As an example of how this might result in pointing and laughing, look at how the public and the media responded to the clothing choices made by Canadian PM Justin Trudeau and his family during their recent trip to India.
I’m not Irish and I have only been there a few times, so I am commenting from the other side of the Irish Sea…
Is the rest of his garb, worn along with the utilikilt going to be generally ‘outdoorsy’?
If so, I would think it’s unlikely to be a problem - although slightly unusual, a kilt like this is not out of place when it’s combined with other clothes that have the general look of an experienced hiker, outdoorsman, fisherman, etc. It will probably still draw some glances and double-takes.
Wearing a kilt of this style on a city centre shopping trip would probably cause a bit more of a stir, but I think it would still be pretty good natured and most unlikely to escalate into physical violence (if someone punches you because you’re wearing a kilt, there’s a fair chance they were going to punch you for some other reason anyway)
Medieval fairs and festivals are a fairly big thing in Europe, though. They just tend to take place in actual castles and medieval towns and have less fur-clad barbarians and chainmail bikinis. Or so I’m told, I’ve only been to European medieval stuff, not American Rennfaires.
As another datapoint from Europe, I had to google “rennfaire” to find out exactly what it was (though of course the general gist was clear from the context). It isn’t a term widely known here but of course we have lots of medieval festival type of stuff.
What a perfect, American answer. I’m going to try it. Quick question though, does the sporran go under or over the shirt?
Also, flip-flops or sandals with black dress socks?
A fanny pack will do.
I just know about rennfaires because I do medieval re-enactment, and we don’t like it when people confuse the two.
Splitter.
OP here. Thanks for all the feedback. It’s nice to know he’s unlikely to get punched in the face. 
To answer some points:
- while he has some (subdued) Hawaiian shirts, we’d never thought to pair them with the kilt. I almost want to see that now.
- the reason I mentioned the kilts are black was already hit on; they’re not tartan kilts, so we’re unlikely to accidentally start any clan wars, they’re not camouflage so he doesn’t look like an NRA member, and they’re not screaming neon.
- the kilt is paired with outdoorsy clothing, for the outdoorsy day trips we’re doing. The plan wasn’t to wear it shopping in the middle of Dublin.
- no, he has no problem being thought eccentric. Yes, we are both regular attendees at Renn Faires. I am a previous medieval re-enactor, and back in high school was a routine wearer of punk pin-and-leather outfits.
- the purpose of wearing the kilt is comfort, ease of movement, and temperature control; same reason to wear it here at home in the US. That, and I love the way it accentuates his calves.
- as far as I’m concerned, Justin Trudeau can wear whatever he wants. That man can do little wrong. Also, he’s scorching hot.
Again, thanks for all the data points!
Point of view from the UK.
The colour is totally unimportant
Wear it if you want, but be prepared for EVERYONE to be laughing at you behind your back
and sometimes to your face.
You will be stared at everywhere with people pointing at you. If you enjoy that then carry on.
Let me ask the nay-sayers this: would you say the same about a utilikilt in the USA? In other words, do you think it is silly for a man to wear one ?
The OP wants to know what the reaction will be in Ireland, not a different country entirely.
And the answer is that people will laugh at him, not with him, and definitely pass him off as eye roll worthy.
But thats all, the idea that there would be anything more than that is strange to me. Why on earth would there be any violence?
It must also be said that in my entire life the only time I have ever seen a kilt worn is by a Scot at a wedding. They just aren’t done here.
It is well known here, that if you are in Scotland and see a person wearing a kilt, it’s another Australian.
But maybe that’s just a story we tell ourselves.