I assume this is in response to the resin component near the skin.
It seems there is a strong bias in the Aussie region against mangoes with any kind of resinous component towards the skin, what is commonly sought after in India and the Caribbean. There are many kinds of resin that you can find in mangoes, with the kind in Keitt likely being passed down from the Haden (which got it from turpentine). I'm not a fan of that resin either, but I do strongly favor other types of resin in mangoes like Kesar, Alphonse, and Julie. I actually love Keitt, but quality in commercially harvested ones varies so strongly due to cultivation and harvesting practices that I would recommend growing it yourself and harvesting a well grown and ripened fruit before judging.
On the topic of resin, many people stateside call Aussie mangoes resinous, judging the strong parsnip flavor near the skin as a chemical component, so taste preferences vary greatly with region. Mangoes like Bowen and Maha would fall under this group.
That same resin you dislike is present in the mango favored in South Florida (CAC or COC), and it also has the parsnip flavor, so you will find people on both sides of the pacific who dislike this one as well based on resin.
Very few of the American ones are descended from Keitt with a few notable exceptions, but many American mangoes do contain a resin component Aussies will dislike. That said I've tasted quite a few of the newer selections, and I don't taste it in any of the newer ones like M4 or Cotton Candy (both Keitt seedlings), nor do I taste it in any of the Kent descendants.
Kent has a resinous component from Haden, but it isn't anything like the one in Tommy or Keitt.
Try getting a hold of the Guava or Sein Ta Lone mango if you can, it has an altogether different resin, but it's got a lot more going on and is fantastic (poly too).
Hey mate i think you have nailed the answer, I also did a bit more research on here and it seems that the legendary Mike T has made many comments before on what im trying to describe and he describes it as a hydrocarbon taint and this is exactly what I have found and am trying poorly to describe.
You have covered it well the taste was worse near the skin, and yep none of our aussie varieties, KP and its many prodgeny such as honey gold etc nor do maha or NDM have this trait. Certainly there is a major cultural aspect going on here as to what each place prefers and thats why the issue of americans not rating our mangos highly and vice versa.
I have seen recent reports here of lemon zest and fruit punch and other zill trees grown in australia being compared side by side by multiple people with KP and KP variants and almost no one rates even these new ones as superior to KP, massive cultural difference for sure