Weirdly, I know the answer to this.
I can’t find the article now, but back in 2016ish, there was an article (in Variety maybe?) in which a journalist did an investigation on this.
Back in the days of the Apprentice when trump was regularly made up by a pro for television, he was very happy with how they did his makeup and asked what made his skin look so much better. The makeup artist was using a high-end Swedish concealer and told him that was the secret.
Unfortunately he’s an idiot, so he misunderstood the point of it, and ever since, he imports that concealer and uses it alone as an all-over makeup.
I can’t explain why he thinks using it this way looks good, though.
Oh wow, that’s still a thing?