Thickness also plays a part in looking hung, though I understand the term “hung” implies hanging down. Since I’m 4 1/2+ nbp flaccid hang (and just 4+” flaccid girth), and it doesn’t look impressive to me, I can’t vote for 5” nbpfl.
To me a nbpfl hang needs to be at least 6” to be called hung. Having flaccid thickness enhances that term, and thinness can take away from it. Afterall, if a guy has 6” nbpfl and 3” flaccid girth, he’s not likely not to be thought of as hung is he?