Ok. The thing is dressed well and mannered well person will definitely impress a girl. But It requires effort and mostly motivation. "looking good" can not be everyone's priority. If your life is going not that bad, you will give priority to dress well and well mannered, but if your is shit, there is a less chance you will give "dressing well" a priority in your life. Same person, put in different life, and you will get different results. I am from poor country, when I was in college, only 2 out of 10 students were well dressed, and now I am in one of the western country, I am seeing almost 10 out of 10 students are well dressed. Because in my country, priority were different. So understand this frist. Now about the answers you got, frist of all no one knows what you are going through, there are just seeing the output. And no one is going to say the problem is your stutter because no one wants to look like a bad person. See it is not you will not get a girlfriend because of stuttering, you will, but communication plays key part in any kind of relationship, so also understand this, don't be hard on yourself. Definitely if you can, workout, dress well and smell good, you will increase your chances but don't compare yourself someone who can make communication fluently. Communication does matter in any relationship and stutter becomes hurdle in doing it.