No scandals have hindered Trump so far
Melanie Trump has been caught plagiarising Michelle Obama. With any other presidential candidate, this would've been a farce which could prevent presidency altogether. However, the current political situation in USA is rather absurd. As majority hates both candidates, just one more than the other, they side with the one they deem "lesser evil". Therefore they don't really care about scandals of this nature. The goal is just to keep the other one out of office. Furthermore, Trump has had so many scandals that one more doesn't make a dent in his armor.
I think the plagiarising was a setup so Trump can get more publicity.