There are many factors that compound the difficulty of providing some kind of verifiable proof that the Astral projection really took place within the physical realm (see maps of the Astral).

Here are some quotes, to be used for this article:

Monroe, Journeys out of the body, chapter 4:

Time away, eighteen minutes. Comment: No connection with Dr. Puharich's activities at the time, as he reports. Wrong destination again, no validation possible. Why does my presence
create such fear?

This inability to control destination has been and still remains the chief barrier to the production of consistency and repeatability.

In the following quote from the same chapter, Monroe clearly states his belief that a large scale validation of OBEs could be performed is more people joined.
But again, the difficulty of bringing back physically verifiable data is noted.

Time away, forty-two minutes. Comment: Through a check by phone, I have located this family at the address which the man gave me. Would it be appropriate to visit them physically on some pretext?

From this, it can be seen that a much more extensive and organized effort would be required for massive validation of Second Body activities in Locale I. One subject and several assorted scientists and psychiatrists are not enough. Also, it can be noted that unexpected visits to unprepared persons can't be helped at this stage of control. Perhaps much could be gained if such people could be interviewed as to what they saw and felt at the time of the intrusion. The difficulty lies in locating these people. It is the exception that enough data is obtained to identify the place visited, as in the above.

Visual impressions of the physical world as seen from the "Second Location" is also greatly impaired and registers in shadings of black and white with strong light and reflections playing tricks on the Astral observer.

Also Monroe notes in several places that he's had 'conversations' with people who were at the location observed at the time of the projection, but the person denies recalling any such conversation when asked about it later. Thus, it seems the traveller is communicating with an unconscious part of the subject rather than to its day-time conscious persona. People in Monroe's entourage suggested in fantasized the conversations. 1

• 1. Chapter 4