Interesting, that last line. Does that explain why some of these boats smell
like unburned gasoline's blarping out of the exhausts,

That is exactly what is happening. A high performance cam will hold the intake
and exhaust valves open at the same time, longer than a normal cam. (overlap)
At high RPMs when air is flowing fast and plugs are firing 50 or 60 times a
second, that is a good thing but at lower RPMs you are actually sucking intake
mix directly into the exhaust.You can also be popping back through the carb.
You will see the same thing with race cars ...
....and 2 strokes.