Is it a mistake to tell a client you are busy when you actually have no work?

[Btaliat]

It is not really a mistake when a freelancer create artificial scarcity for himself. Clients always willing to pay high for the freelancers that don't have time and seem busy. In fact, they will count themselves lucky having such clients. Unlike freelancers that are always free, they will not really be rated. They will believe they don't have many freelancers to be hiring them. Sometimes they even reduce the price they are meant to give them.