When one looks up the meaning of the word “sincerity” you’ll most likely get a definition like this:”the absence of pretence, deceit, or hypocrisy.” That pretty much nails it.
To answer your second question: When someone is “sincere about something” one assumes that this person is thinking, talking, acting and writing without “pretence, deceit or hypocrisy”.
One would assume that EVERYBODY acts/should act/would have to act sincerely ALL the time. 😉 IF you need to emphasize that someone is “sincere about something” you’re actually implying that this person/institution/party/
Actually there is a large consensus in most societies -especially in the upbringing of kids!- that the ideal of virtue is to be sincere ALL the time with EVERYBODY about EVERYTHING. Unfortunately this ideal very often gets watered down for the “greater” ideal of “being right” and then being “sincere about something” means that your listener will have to succumb to your uttered perspective/viewpoint/opi
So, in essence: Let your alarm-bells ring loud and clear as soon as someone feels the need to point out that he/she is “sincere about something”. Not necessarily that this person will NOT be sincere, but rather that this emphasis usually means that this person is pointing out something which is quite important for her for some reason(s). Try to find out/analyze about this reason and be VERY wary of it! -quora.com
