Are there many more ghosts than we think?

The overwhelming majority of ghost reports say apparitions look just like normal people. So might there be lots more ghosts around than we think because we just don't recognise many for what they are? I sometimes wonder this when I’m walking along a busy street = could one of those people I can see actually be a ghost? How would I tell? Might they behave in an unusual way, for instance?Anyway, I was walking up the long walkway access to a footbridge over a dual carriageway recently. The bridge was high and the walkway long. A young man in a hurry passed me going in the opposite direction. He turned to look at me as he passed and grinned which I thought unusual.I carried on up the walkway but after a few seconds remembered ghosts! I turned and looked back down the walkway. There was no one in sight. No one could have left the walkway without falling or jumping a significant height. So where was the young man? If he had vanished then he might be a ghost!The walkway was so long that it doubled back on itself. So, I looked at the lower section. There, right at the bottom, just about to go out of sight beneath the bridge, was the young man, still looking very normal.  To have gone all that distance he must have started to run after he passed me. If I had not seen him at all the second time I might have seriously considered the possibility that he had vanished and was indeed a ghost. Recognising ghosts is difficult! Maybe they really are much more numerous than we think.