Most of us human beings have at least one emotion that we have difficulties expressing. It's not that we try to express it but it doesn't come out, what usually happens is that the emotion comes out with a different expression.
Many people meet nervousness and guilt with laughter. Men often transmute sadness or frustration into anger. Women tend to cry out of overwhelming emotion, regardless if that emotion is sadness. Loneliness is often expressed as contempt, and so forth.
The source of this phenomena is to be discovered by the person who experiences it. It may be culturally inappropriate to express an emotion in public, it may be that one's parents dissuaded certain emotions from being expressed. It may be one's own judgements about a particular emotion.
The problem is: the person who experiences it rarely notices the phenomena. You may be angry at someone and the other person laughs. If you have difficulties reading the situation you could interpret the laugh as contempt, which makes the situation worse. Drama therapy is great for getting feedback on how you are reacting to certain emotions, should the reader feel that this is a challenge to be addressed (you are perfect as you are, nonetheless).
I've known for a long time that I have difficulties expressing anger. At times, when I would have expected to become angry I've felt a sinking feeling of sadness. But today, seemingly out of the blue, I got angry and was actually surprised at the emotion and the result.
I was running an errand when I came across what is considered the fanciest gym in the city. Even though I can't afford it at this time I wanted to check it out, in case the future holds a better financial situation.
I went in and said I wanted to check out the gym. They assigned me to a sales agent who sat me down on her desk to get my personal information. She was really clumsy at the keyboard and had lots of difficulties spelling out my name and email address. In the middle of the process I said "Look, I just dropped in expecting to check out the gym and figure out the prices. I don't think you need all my personal information". She repied they needed my email address to send me the rates. She went drilling more questions until she asked "where do you currently go to the gym?" and I replied "that's none of your business". "Look", I said, "I don't have the time for this and it doesn't seem we're a good match. I will leave now", to which she promptly stood up and said "never mind, let's do the tour".
As the anger was simmering I was a bit of an asshole, or assertive, depending on how you perceive things: "I'm not interested in the cardio machines or the bikes, let's move on". Then as the emotion receded I became more agreeable, but by now I was leading the tour and she was following me explaining what I was seeing (which required no explanation, really).
We parted ways in good terms and I felt emotionally refreshed after leaving the building. The anger was not expressed as verbal violence towards a person, it was expressed as having the assertiveness to walk out of senseless procedure. Should I deal with it as I usually do, I would have put up with their sales tactics and standard tour and I would have left annoyed, saddened and exhausted, knowing I would never consider becoming a member. Instead, a moment of anger steered the events towards a better outcome for both of us.
From both spiritual and evolutionary points of view, emotions exist for a reason. There are no "good" or "bad" emotions. Though we do need to possess a certain degree of emotional regulation to live in society, obstructing an emotion it like obstructing pressure: either it finds a different route to find release, or it explodes in your face.