When machine prints, you expect dust will be on the moisturized area(when machine printers, ink come and goes, there is the moisturize). Just open up the control panel, if it is dusty and not clean, it's been used.
Reason is that I recently visited a new customer. He bought the roland sp540p for over one year(the warranty expired, we went to service), we opened up the control panel and it looks brand new. The location is in between busy cross streets in los angeles area. Door is always open. He only ran machine once. Just my .002.