In Ghostbusters, during their first job capturing Slimer in the hotel, Raymond warns Peter and Egon to not look directly at the trap as he opens it to capture the ghost. Egon states that he looked at the trap, and he suffered no apparent ill effects.
What did Ray fear would or might happen if someone was to look at (or into) the trap?
While some fans have stated that the soul may become trapped, the common conclusion is to prevent blindness. Also, they DO look at the trap, while wearing goggles in the second movie.
From ectozone:
Do not look into the trap: It is not stated what exactly would happen if a human were to look into a Ghost Trap, however it is believed by most that the glare could cause eye damage and even blindness.
From gbfans.com:
In Ghostbusters, Ray advises Egon against looking at the trap. In the Braxtan fanfilm, Return of the Ghostbusters, this comment is expanded upon, the characters describing how the soul can be pulled through the eyes into a trap, subsequently being stored like a ghost.
However, as evidenced in the films it is more likely that looking directly into the trap will blind you, not steal your soul. In Ghostbusters it was simply that Egon was not close enough to be blinded by the trap, but was clearly bothered by looking into the Ghost Trap.
