"He might have been being facetious."
OR
"Diamonds have been being mined in South Africa for years."
OR
"His plans have been being sidetracked for years."
Why would people use such a grammar construction?
***** NOT A TEACHER *****
(1) Mr. Swan tells us that perfect progressive passives
(has been being) are
unusual.
(2) To understand the next item, it is necessary to know
two words: to initiate (to introduce a new member into a club)
and labored (something that is difficult to do and is not very
smooth or elegant).
Harper's English Grammar (by Professor John B. Opdycke) tells us
that "At this time tomorrow I will be being initiated" is
correct and
intelligible, though
LABORED.
(3) Finally, Professor Quirk and his distinguished colleages tell us that
we can change "The Conservatives [a political party] have not been
winning seats lately" to "Seats have not been being won by the
Conservatives lately," but he says this is
RARE and he even uses a
question mark (the authors are not sure whether such a sentence is
"good" English).
The professors add that maybe one reason we avoid this kind of
passive is the double use of "be": be being/ been being. It is
"awkward" (not smooth) sounding to native speakers.