The three dealers around here rate them above average. They say they have very few problems from the ones they have sold. I don't have the failure rates world wide for Kymco. I don't believe any one does. Most would just be familiar with what is happening in their small portion of the universe.
Don't know if one small statistical distribution in one location could predict the overall outcome in the total population. There could possibly be too many variables at work.
In most cases and especially in USA, scooters are "leisure vehicles" or "something for fun", more of an "oddity", than vehicle that is used daily.
Only when you drive it as a primary vehicle, and own a number of them over a longer period of time, you can truly see what is their build quality... and of course it is better than anonymous Chinese crap, but it is substandard nevertheless...
I said this many times and will repeat again, some solace can be found in fact that nowadays I have no idea what "good quality" scooter brand would be, especially for these little scoots and <500 cc. Pretty much all are made of cheapest components available and they are not made to be durable, but to be replaced every two years as design and marketing paradigms shift.