“I also didn’t like the use of the EMF detector (????) if they knew they were looking for a demon. That’s only for ghosts!”
Yeah. I attribute that to the writers needing a little more time to get their legs under themselves. When the brothers were in the hangar looking for the cause of the crash, Dean’s EMF meter went off when he approached the emergency door handle. It was only afterward that he noticed the sulfur.
I’m annoyed by the inconsistency, but I suspect the writers wanted to make it harder to identify demons later in the series. They got rid of “Christo” pretty fast, and dumped the EMF tool, too.