In my book --but YMMV-- anything which allows one to distinguish between one AM and another AM, takes away his anonymity. Whether this is between threads or inside threads only, makes no difference to me. I am already anonymous by using a self-chosen nickname here, so using the robes of AM has nothing to do with being linked to a real world physical person, but it takes this basic anonymity which we can all enjoy already to a next level. Distinguishing between AMs takes this ability away.
A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James