The first method is to make an effective and shocking door sticker, which makes people afraid to knock on the door of your dormitory, and even more embarrassed to come in. For example, in the picture below, they want to sell these things, and when they see the door stickers, they won't knock on the door. This is a trick to keep them quiet. Or put a senior on the door, and the salesman will know that you are a senior, so don't bother. Pretending to be a senior is very useful. I remember when I was a freshman, I didn't expect this move. I experienced a lot of salesmen knocking at the door, but no one knocked at the door when the dormitory next door posted this. Another way to refuse is to lock the door when they knock. As long as you don't open the door, they won't keep knocking. They will go to the dormitory next door.
The second is to refuse to get too close to the promoter. In the process of sales promotion, they will want to chat with you, get on well with you, and then sell them to you. Don't fall into the trap. If there is no door sticker, the door is unlocked, and the salesman directly enters the door to befriend you, then you need to resolutely refuse them. Don't hesitate, otherwise they will feel that there is still hope and the promotion time will be longer. Don't ask me why I know, just say that I have experienced it. One day when I was a freshman, the door was unlocked, and as a result, a senior sister knocked at the door and went straight in to chat with us about Korean dramas. At that time, we were embarrassed to refuse and our attitude was not firm enough. As a result, she talked for four hours in our dormitory, so let's call our parents for advice. I really want to avoid this situation, and don't let them feel that chatting with you is long enough and intimate enough to make it difficult to refuse.
The third is to strengthen your beliefs. Don't forget that your initial idea was to refuse. Your tone must be firm, don't hesitate. If you hesitate, you will fail. If you want to refuse the sale, you must refuse it from the beginning. The first step is to put an end to sales promotion. Then, if you enter the door, you will refuse any sales promotion from the beginning, behave badly and have a firm attitude. They won't waste too much time in your dormitory, and you won't waste too much time dealing with their sales promotion.