An interesting article appears on the Paul Fraser Collectibles website about about a scandal involving Apollo 15 astronauts back in 1971.
According to the piece, Apollo 15's Commander David Scott and Lunar Module Pilot James Irwin brought 398 commemorative postage stamp covers with them on their trip to the Moon, with the intention of selling some of them to a German stamp dealer after returning to Earth.
The plan was to sell 100 a German dealer and the other 298 kept to be kept by the crew themselves.
The article goes on to say, "It eventually emerged that the astronaut's profits would have been used to set-up trust funds for their children - an arrangement which was in no way illegal, and which NASA had actually turned a blind eye to in previous space flights.
"Neither was it illegal, nor prohibited by NASA at the time, to take souvenirs up into space. Apollo 15 actually had 243 covers on-board which were authorised by NASA, along with the 398 unauthorised covers.
"But Scott, Worden and Irwin were deemed an embarrassment to NASA and the Apollo program, and subsequently made an example of. The trio were dropped as the planned back-up crew to Apollo 17, and this effectively ended their career as astronauts."