Take a look at this article: http://meditationmag.com/meditation-psychology/nice-vs-kind/

I see a lot of people take the advice to not be a nice guy and take it too far in the other direction. Yes, being a dick will work to get girls, but if you are looking for quality or if you are not the kind of person to be a dick all the time, be kind.

Being nice doesn't work because it is rooted in fear and is a quality that is used to try to get people to like them. It is reactionary in nature and people see the lack of self worth it portrays. That is not attractive.

Being kind, however, comes from a place of confidence. It is proactive and is not an attempt to get people to like you. It is showing genuine empathy for another, or just making someones life easier because you can, not because you think you should. This is an attractive quality.

Don't be nice, but you can be kind. Nice people are pushovers, kind people aren't. Nice people neglect themselves, kind people don't. Nice people sacrifice themselves to others. Kind people share themselves to others.

Just a thought.

TLDR; Not being nice doesn't necessarily mean being a dick, you can still be kind. Do something for someone because it makes you happy, not to get them to like you.

Edit: Grammar