If you know that person very well, yes you can read them. If you do not know the person very well then it is almost impossible to read a person. Texts, words, emails, etc. can mean and be interpreted so many different ways. Everyone is also very different and reacts and has emotions differently.
When my husband and I were dating he would say things and I would just stare at my phone wondering what the text meant or if I said something, I would be wondering what his reaction is. Two years after dating and now being married, I can literally picture his facial expressions, mood, and tone when he or I say something through texts, emails, and words.