There was the following passage in Maureen Dowd’s article titled, “Hooray for Hillarywood?” in New York Times May 30 issue:
“You hear plenty of complaints about the president’s mingy care and feeding of donors. “It’s not unheard-of to think that liking people is part of the job,” one political in our consultant to the stars said tartly.”
I don’t think I’ve heard the phrase, “It’s not unheard-of to do” so often.
Google Ngram shows that the incidences of usage of “It’s not unheard of …” is more than 1 digit lower (0.0000004080% in 2000) as compared with that of “It’s not unusual.”(0.000006443%).
Can I use “It’s not unheard-of to do” in the same way as “It’s not unusual to do,” or are they very different sets of words?
In Japanese, "聞いたことがない―I've never heard of" is very common, but we don't say "聞いたことがなくない- I've not unheard of."
If a non-native speaker like me uses “It’s not unheard-of to do” in his conversation with native English speakers, does it sound awkward or does it add a flourish?