Perhaps I do it more often.
Few month ago, 1 guy from another team emailed me and ask if he could use 1 of our team's table in the database for him to store some data. My answer to him was a straight no. Actually, if I want, I can make special arrangement with him to share that table. But because I don't like that fellow, I said no.
If another come and ask me the same thing, I would had said yes and assisted that person.
There are also many times where I look at the person instead of the matter. I guess this is basic human instinct ba. If you treat me badly, why should I help you? On the other hand, if you are kind towards me, I'll go all the way out to help you if I can.
Of cos, being pretty helps too. :D