I think it has to stick with the audience. Making a broad assumption, but SU users are bored and looking for something to entertain them. Generally, an ecommer

I think it has to stick with the audience. Making a broad assumption, but SU users are bored and looking for something to entertain them. Generally, an ecommerce store isn't entertaining (although there could be exceptions if it were targeted properly). If you have stickier content (pictures/video/games) I think it works a lot better. I've had a lot of organic traffic from it and it's good to that type of content. I've also paid for similar demographics in the past, if you match it right, you get awesome returns (even builds links as they share it with friends). If you're not matching it right, it will be a waste of money but a valuable lesson.