Scarcity can be good or bad, for one people want a lot of the same thing and sometimes there's no way of giving said material that everyone wants. That's the bad in a way, but, the good is that scarcity creates much demand. The more people want, you should deliver what they want.
I agree. If you have too much of a good thing, people will not be too into buying more of it. It creates demand to have less and this way, it helps you or I know what is needed to be shipped out more. Hope that makes sense.
Um yeah I suppose so. Scarcity can be quite useful to a site, in that it does create some demand. But you don't want to do it for a long time. It's best to give users what they want.