How do you tell who is more dominant than you are in a casual bdsm setting?

Well thats going to be a very personal thing.

If I am alone at an event, or in a chat room, or just walking down the street, I watch how people are interacting with each other and then apply it to my own behavior where appropriate.

Dont get me wrong, I identify as a slave and a Gorean one at that, but that has little to do with how I carry myself with those who reside outside of my paticular condition of servitude or "circle of established dominion" other than I do strive to be a good reflection of my Owner's Dignatas. (I am not collared by anyone but my Owner, so the rest of you "outsiders" are technically free game until proven otherwise by his declaration or me by direct interaction) If my Owner recognizes you as having dominance over me somehow and or decides to share auctoritas (if only temporaraly_ which btw often happens between subs in a poly setting) with you over me, then we have a whole different ball of wax.

Of course if you do something thats just plain not very dominant imho with me, like oh say, begging and pleading for me to do something, or asking me to "fuck your ass good with a strap on while you call me Mammie" then you may find that in my eyes at least, your not all that dominant anymore etc. lol Winks.