How to tell if he wants his cock sucked question

[Sammywho]

Hi new to the gl community and was hoping for a little guidence. My local abs has several gl booths. The times I went I kind of just hung out in the store looking at merchandise and seeing who walk in etc. Being an oral/bottom is there a way to signal or clothing to wear or something like that would let another person know I am an oral/bottom before going into a booth? I just dont know how to tell the difference when say six guys are hanging out in the movie rental department, all of which are going to hit a booth, who wants their cock sucked and who wants to suck... I hope this makes since.. thank u