I suppose it depends on how people do it. If the goal is more self-promotion, or more redirecting towards the cause in question and using that promotion to spread awareness and attract others to the cause. For example, I have no problem when blood drives will use a celebrate for promotion, saying things like this guy has donated every week since he was a kid, you should donate and be like him. That could be considered self-centered on his part to allow that praise, but at the same time if it results in more awareness and more donations, that is a definite net positive in my eyes. Isn't it?
That said, it is a fine line and I don't know if I could draw it well.
Blood donation was mentioned in this comments thread positively already, a worthy cause for sure, especially here where there's not enough blood available.
I think so too. I'd see blood donation, raising money for fighting the top killers (like cancer, heart disease, Alzheimer's, lou gehrig's disease, etc), and helping the poor would all be among worthy causes. Things that help people and help society, mainly. But that's me. I'm sure your list might vary. That said, I don't know if it's a cut or dry issue and is more case by case.
Case by case for me...I don't have a lot of faith in 'charities' as it seems so many of them do inappropriate things with the funds the
extortcollect from others.