Some thing happens when people connect with one another. When they have contact with each other for the first time, it could be that at times it could go well, at times it can be awkward.
The point behind first impressions between strangers is that we may be drawn to one another or drawn away, depending on the "familiarity factor". (As in, do I want to get to know him or her.) These strangers judging each other on outward appearance stoke in themselves memories from the past, people, experiences, or otherwise use visual external cues or in case the matters of others' confidence.
No matter what category the judging is based on, these strangers will have contact that is imminent at this moment in life. Whenever is not the case, but how will one think of it.
If at a time of communicating, a lot more words are needed yet cannot be expressed, then the utilization of non-verbal gestures are necessary. A look can say a whole lot based on the mood or emotion. Why? Because a deed or action to try and accomodate a stranger, as in a smile, accomodating a space in line, or offering a plate can just mean acknowledging their existence.
In order for a true introduction, the stranger can perhaps consider where they are in life, as well as the other person's time in life, and what the other meant by that gesture. It should be all felt wholeheartedly for neither one were meaning to look misunderstood unless it came with character or shyness at that time. Either way, reasons to have a backing to why they look ignorant or disdainful at that time is because of present circumstances of and/or the person's lot in life at this time.