Its a bit like UFO/Alien sightings, which always seem to have an up-tick when people start drinking.
There's also a number of relatively strange physical phenomena that, if you didn't know about them, they could cause you to present them as 'proof' of sprits. For example, when in the presence of low frequency sound waves (inaudible for humans) that match the resonance of the human eye, it can often cause you to see ghostly figures that pop in and out of your periphrial vision. This has been confirmed as the cause of a number of 'haunted' buildings.
Fortune tellers are just con artists taking advantage of the human weakness called confirmation bias, or in some cases, they do lots of prior research on clients in order to appear as though they posses supernatural knowledge. There's been so many examples of these folks being debunked that I feel like your inclusion of them in your question may indicate that you're attempting to troll us a bit. Just because someone doesn't believe in god, doesn't mean that their mentally acute and able to recognize when someone is taking advantage of them and manipulating them.