Man About the House: And Mother Makes Four

Man About the House: And Mother Makes Four
ITV
22 August, 1973
Sitcom
DVD
B-

I've obviously seen this plot multiple times, on Three's Company in particular, but this time I was really struck by how foolish it is not to tell the visiting mother about the male roommate.  OK, so she doesn't visit that often.  Still, it's not the kind of secret that could be kept for long.  Interestingly, Chrissy's mother fears her marrying a black man but she has no qualms about her living out of wedlock with a white man.   So she's racist but not old-fashioned?  Or does Chrissy just not know her mother very well?  It's also a non-issue when Mrs. Roper finds out that Robin isn't gay.  And both Robin's "dirty" lamp and Mrs. Roper's book cover show more nudity than could've aired in America at this time.