Yes and no, in my experience you can tell what a person is like by observing them or being in a social gathering with them. One can tell whether someone is loud and likes to be the centre of attention or the one always talking. One can tell if someone doesnt say much nor doesnt join in much on the conversation but it doesnt definetly define whether they are submissive or dominant. For myself, I can tell whether a girl is dominant by how they act and talk, some girls are just fiesty and dominant that one can tell from the onset and one would know who wears the pants in that relationship. However I have known for some girls, its just something they appear to be like when they are deep down submissive and are just looking for someone with balls to give up control to.

Whereas I myself is a perfect example of this, I am not very dominant at work or in a social context and can relate to the category where I dont need to be the loudest one in the group or always being the instigator of fights and arguments and rather let things be and avoid conflict. However I am dominant and in relationships like things done my way and having a girl to look after and be submissive to me.

So in answering your question, in my experience there are the extreme people who definetly fall within one category or other by their behaviour and actions, the type who are shy and the extroverts but for all the people that fall in between those extremeties, its harder to tell. And no you cannot definetly tell whether someone is dominant by just looking at them on the street...Ive found that out the hard way, when I thought this sweet innocent girl was cute then she spoke and boy did she have a mouth on her!

Hope that helps!