Dunneh writes in her post on Narcissism is my forte about product demo's. She has important and interesting points.
I myself have not used demo's much yet. I came to SL without any money and have only recently gotten some SL income. So I would not have had the money for the product, so I did not use the demo's much. I might have tried something just because it looked awesome, of course. :)
See the post and make up your own mind. Should demo's be always free? I agree with Dunneh in that a free demo gives a generous impression of the store owner. But now that I have some money to spend, I like the idea of supporting the designers and 1l for one demo is kind of a nice way to say thanks, if I end up not buying the product. But that's also why there are donation jars at stores and Dunneh makes good points about demo's when you are someone who uses a lot of them.
Maybe there could be a group for demo users? You could get demo's for free if you were a member? Joining a group requires some initiative and for that I think it's a good thing to give them a free demo. And I guess as the group tag allows the freebie, it gives the seller a way to track how many demo's they have sold for free.
What do you guys think?