Sometimes it works in both modes and you are not too sure. For example:

… but also

The sepia monochrome version has a gangster undertone to it (which I like): the distinctly dodgy face talking on the mobile, two chaps conversing, one looking furtively at the disturber of peace (me, between flights). Enter mafia boss… ))
The colour version is atmospheric and kind of romantic: the plant imitating the wall paper, the woman’s stare into the lens, her clawed fingernails…
Moody or romantic?
Oh well… I just shoot.