Do you bottom to your employees at work or to your children when they they misbehave? Do you top the police oficer who has pulled you over for speeding or the coach of your basketball team at practice?
The above situations and whats considered appropriate interactions within any given dominance heirarchy between individuals is much easier to understand than judging if the person you meet in a club or some other setting (yes even online) is more or less dominant than you are, but thats only becuase they come to the table with recognized positions of auctoritas as opposed to dignatas which is somewhat more subjective.
How submissive or dominant one is with another person often depends upon the situation and the idividual dynamic between those involved.
This is especially evident when one is in a poly-group setting such as a formal "house" etc where there is often a Prime or Head Dominant or council of such, holding dominion over not only the subs but the other dominants as well and often times a "First" girl or Alpha sub, is given authority over the other submissives with varieing degrees of decending authority extending down within both the dominant and submissive quarters etc.
Once you wrap your head around the consept of existing in an dominance hierarchy in your day to day life (even if its unwritten most of the time) then you can realize there is no need to divorce D/s from your day to day world since it exists everywhere all the time (in other words the D/s aspect of bdsm is indeed a part of the world too, not some seperate thing that exists outside of normal vanilla behavior its even apparent in every level of nature from the micro to the macro level ) there is no more need for confussion anymore as to weather or not one is a "submissive" or a "dominant" since in effect we all switch behavioral orientations accordingly even if only on a sub-conscious level.