I'm unfamiliar with the term "photo spray," as is Liz Cox Barrett, writing at CJR. On the meeting between Sarah Palin and Hamid Karzai:
...At this point, the pool was hustled out the room and down to the hotel lobby.
Pool was in the room for a grand total of 29 seconds.
Palin spokesperson Tracey Schmitt gave a statement to reporters in the lobby as to why print pool and wires were not allowed in:
“The decision was made for this to be a photo spray with still cameras and video cameras only.”
I’m not familiar with the term “photo spray,” but I do think it’s more apt that “photo op” in that it doesn’t imply that something is being given (the campaign provides the press an opportunity to photograph the candidate… in a specific, controlled manner) so much as something is being forcefully dispensed, like pesticide on a pest.