It could be these anxious financiers were just keeping an eye on their investment, or they were there to make sure that nothing would be printed that was offensive to those in power. Printing offices, like the monasteries, became a center for scholars and new ideas. Many printers employed artists to do illustrations and design the type and books. Scholars were brought in to do translations. Aldus Manutius employed the great scholar, Erasmus, to work in his publishing house in Venice.
Some old illustrations show stacks of completed books and pamphlets.
These were most likely the product of the shop and were offered for sale. The print shop served as book store as well. The shorter, less expensive pamphlets offered a more steady income to the printer. The subjects were numerous and mostly enlightening, but even the religious works pandered to the masses with violence and sexual content to make the more conservative members of society question the bad influence that the new media had on society. It didn't hurt when the print shop was near a port or was a mail drop for the post rider.