I hate when girls try to act too cute. Its just annoying and deceptive.Ehh... I just avoid moe girls, it's easy enough to detect and just download something else. It's not exactly excess moe would cause fapping failures, but if I found a girl to be too cute, it's only a few clicks to bring up another JAV. In a pinch, even any old old vids by Maria Ozawa or Takako Kitahara.
BTW it's rarely a girl IS too cute, but she can ACT too cute. Most girls over a legal/moral age is "functional" enough, but a girl can ACT moe (dressing, make-up, mannerism) to the point of deflating a perfectly fine erection.
But when a girl is legitimately shy and embarrassed that is the best kind of cute. I find that kind of shy cuteness irresistible.