First of all these are "women" who are are sexually matured and legal, and they have everything in the right place, so I would be interested to hear why someone would find that disgusting.
Many 18/19 year old girls may be physically mature (just) and may be able to bear a child but that does not mean that they have the emotional maturity to handle sex or to have any kind of equal relationship with a man 19/20 years older than her. The average 18 year old has very little experience of life and often has had no time to fully formulate her opinions about various subjects or her values and principles, consequently she is much more open to exploitation and 'moulding'.
A man who is considerably older could easily manipulate both the girl and the relationship to his advantage. How can you debate or discuss the world when someone has the upper hand in experience and learning opportunities. I'm not against age gaps per se because by the time people reach their late 20's they have usually gained enough experience and education for the gap to be less of a drawback. It's the ability to exploit that is disgusting.
As for your 'cringing' about the woman being 52, she could be stunningly beautiful, you can't always say, beauty is in the eye of the beholder.
I have always thought that white men age appallingly badly, at 18 the thought of a 37 year old white man would have made me heave but if my mates had gone after one my objections to the relationship would not have been based on my idea of physical beauty but on the fact that the guy was in a position to exploit because physical attraction is subjective.
What exactly do YOU get out of a relationship with an 18 year old other than sex?
Can't you see that an older woman e.g 30 would have so much more to offer and still be beautiful.