This is true if by "nice" you mean attentive, respectful, concerned, etc. but only from a position of
not having to be. When I was in college there was a famous case of the very average guy who had snagged an unbelievably gorgeous girlfriend. I asked around about it and found out she'd told someone he was the only guy she'd ever met who respected her as a person and wasn't just out for her body.
Observing him, though, it was clear he also projected the confidence of someone who would not crumble into a heap and die if she dumped him. He seemed like his own person, like he owned himself, like he had a life focus. That is really the only reason his attention and respect meant anything to her.