Fair enough.
So I did a little checking...
On Apollo 12, while he was inside the LM, Alan Bean took four photos of Pete Conrad out on the porch (AS12-46-6715 to 6718). According to the ALSJ, Bean held the camera upside-down (and at knee level) to take the four photos. On the LPI site, 6715 is shown right way up, while the other three are shown upside-down.
I checked the photos in question on MTTM, and all four were upside-down.
So I think it's reasonable to assume the MTTM photos are all aligned as they were taken - so, sometimes, for various reasons, the astronauts held the cameras sideways or upside down.
This video of Dave Scott tripping on a rock also shows him using the camera with the 500mm lens. I can't tell for sure, but I suppose it's possible he's holding the camera sideways: