......
......I should have really, really corrected the misunderstanding, that Hetare clearly means useless in Japanese much earlier, though I didn't know it had been spread and fixed that much in Western fandom... and I didn't check the main comm so often.
Well, even us Japanese find it kinda hard to define the word perfectly (also it was originally the word spoken mainly in the west part in Japan and I'm from the east part), but "useless" is too strong a word and beside the meaning pretty much.
Anyway, I looked the word up much more closely and now can tell that "useless" is definitely not the right word for it.
So, Hetare is supposed to be, a person who is quick to whine/complain like letting out a fart originally and then also can mean having a weak will and body, being unresolute and unreliable. That's it. (Well yes, it's not a truly nice word to be thrown at.)
However, the word Hetare also connotes the feeling that "but you can not really hate the person, s/he has lovableness somehow" and most importantly, technically it's possible for a Hetare to be useful.
It's true that it's an offensive word though, but not downright offensive necessarily.