Shoulda, Woulda, Coulda, Didn't.
That's what I say to people who tell me 'you should have'. I take great pleasure in reminding people that tell me 'shoulds' and 'musts' that I am a human and so are they. It is best to remind such people that they are dwelling on the past. It is not something that can be changed now. Nor might you even remember that you 'should' do as such in the future. It is not something you or they have control over and so they are wasting their energy and being disrespectful attempting to tell you off or something. Yes you can endeavor to 'do the right thing' more often, but it is impossible to expect one to do the perfect thing every time on cue. Even people that have been practicing something for years screw it up sometimes. To get something right the first time at the perfect moment? Inconcievable! I would not even expect somebody to get something right on the tenth time. I would expect them to try and so a gradual increase in the frequency of getting things 'right' to a high level may occur, but I do not expect it. So people that try to expect that of me are promptly shut down and ridiculed. If they are persistent I take steps to remind them of their own imperfection. If someone is b*tching at you just turn them into a hypocrite and make snipes at them. Often simple to do when you actually look for their mistakes.