When should you offer advice? When should you be a friend?

See, sometimes, I don't think I should offer any piece of advice or be there as a friend. It's not because I give pretty stupid ideas. I do know though that sometimes people ask questions not really to to ask for your advice but to have someone to talk to about what is bothering him/her.

I don't think I should offer what I have in mind and be a friend at times because sometimes there are other reasons and I think I only become selfish in the end. And I hate myself when I do that. And sometimes, I do not even know if I am being too obvious or if they are just too dumb not to see what I am doing.

For most instances, I think that there are really no selfless acts. Just as what a Friends episode told, each act is a selfish act  because no matter how you try to help out other people, there will always be something in there for you.