"Just like a Kintaro-ame" means "no personality, therefore not attractive"
It was invented in the middle of the Edo period (18th century).
In old days, they sold it at festivals/markets, shouting "Kintaro came out of a candy", and children loved it.
Even now, the manufacturer established a long time ago, called "Kintaro-ame-honten", still produces the Kintaro-ame. For your information, it is located at 5-16-12 Negishi, Taito-ku, Tokyo.
...........HOW TO MAKE KINTARO-AME...........