being nice, nay?

Nice is something subjective. Whether you are nice or not, let the people judge it. 

You might be considered as nice by the person you are nice to. While on the other hand, you might also be considered not nice by the person you are not nice to. 

Therefore, you shall be nice in certain parts or situations and you shall not be nice in the other parts or situations as well. It after all depends on how comfortable you are in controlling the situations.

Sometimes you try to be nice to the person that you do not like. (its all about nice though, you like the person who nice to you, and should you do not like the person who aren't nice to you. ok that's how the term 'what goes around comes around' actually mean) Back to the topic, sometimes in order to make you feel better in being hated, you should do nice to them too, but not too much. Only to the point that it reasonable enough for anyone couldn't call you a foolish person for being nice to someone who hates you. You know, you're doing nice just tp make things look better either through your eyes or anyone's eyes. Meanwhile, you shouldn't (sometimes) be nice to the person who hates you; as part of self-respect. You deserve to be treated better, so why bother being nice to those who aren't (to you) ? It's like you know you won't be appreciated in whatever way it could with that particular person, so don't waste your time being nice to the wrong person. 

On some other points, certain people would love to be with you in certain situations and certain people might hate to be with you in that particular same situations. It depends. 

and sometimes, no matter how nice you are to that person, that particular person still doesn't treat it as nice. and sometimes it would be the other way around.

And in the end, it'll return to how people see and judge. But know that, none of those are matter to you.

Keep your head up, and walk away.