In my twenties I was kind of a tell it like it is person. I grew up in a tell it like it is family and that was just normal for me, I also have ADHD and at times didn't bother to filter. I got along well with people but in my early twenties I started to get feedback that it came across as mean and insensitive and so I worked hard to be very polite / refined and diplomatic and to communicate effectively. This worked great for about 20 years. At one point I taught courses on communication! About 5 years ago, in my 40s, I started to feel that approach slipping and a few times just out of impatience, either snapped at someone or said what I really thought. It didn't go over well! I spend the next couple years still being very diplomatic but with a lot of more snappy, impatient comments in my head that I had to work hard to keep to myself.
I am now late 40s and for some reason I just find it really hard to be patient and diplomatic anymore. I don't know what has happened but my impulse control and my patience leads me to reacting and saying things that clearly have an annoyed or critical or irritated or done with this tone. I don't know why I can't communicate as well as I did. I don't know if it is age or a mood thing (I am not depressed) or hormonal and some kind of premenopausal thing. Near the end of my last job when I was very fed up with the place, I said quite a few things near the end that didn't need to be said. None of it is untrue - I am just voicing thoughts that should stay in my head.
I started a new job 3 months ago and I have already TWICE let it happen again. Once in an email and once in person in a large meeting. In both cases the frustration was warranted for the situation HOWEVER expressing frustrating in a barbed and impatient and direct way is not the way to do it. I spoke to someone who had been at the meeting and she said "well it was pretty straightforward but I think you just said what we were all thinking". She said she didn't think my words were inappropriate but that my facial expression showed a lot of annoyance. It definitely gives you a reputation as I have learned in the past.
I have found it frustrating over the years to supress being straightforward, direct, state my opinion etc in the name of diplomacy but I also think that just saying what you think in an impatient or annoyed tone is not the way to go. I don't know though how to go back as it feels out of my control, as though have lost control of my dont blurt things out response or to not just hit send on an email!
Reasonable: By this point in life, just say what you think but work on tone
Unreasonable: It is bitchy and you need to try to go back to being diplomatic.