I can certainly agree with you that some, or even the large majority of so-called sightings, can be characterized as unreliable eyewitness testimony, from passing glimpses or 'short duration' experiences.
Where you lose me is insisting in an absolute that every single sighting experience without question is people being unreliable witnesses, or of short duration, etc. If eyewitnesses are 100%, without question, unreliable, why do eyewitnesses play such a large part in judicial proceedings? Why do cops and detectives interview people or bystanders from a crime scene? It would be totally useless if what you are saying is true - that eyewitnesses are absolutely 100% unreliable 100% of the time.
I will grant you that humans are an imperfect species and eyewitnesses should be considered unreliable a large majority of the time. But to suggest otherwise and insist that they are always wrong without a doubt seems to be really stretching things into an illogical absolute. Maybe it's just me, but I have a very hard time believing in any absolutes.
Anyways, thanks for keeping things civil, I'm sure you've had enough of these conversations at the moment.