There is an organized authority structure.
PUBLISHER > MS > ELDER > CO > DO > BRANCH/GB
The best way to determine this is to ask how power is dispersed throughout the organization. Are publishers, elders, and others of lower ranks given any sort of say in what will become watchtower policy? Some churches actually let members vote on resolutions, or let a congregation send delegates to go and participe in a convention that utilizies some kind of democratic vote.
With the JWs its all about policy and doctrine coming from the top down.
IMO I think that when the Watchtower says "clergy" they actually mean "people that are paid to preform religious rituals". That's what I felt JWs meant when they used the word clergy.
So the issue of no "paid clergy" it is a red herring imo. "Clergy" (in the Watchtower sense as I desribed above) are usually people that have a lower rank than leaders at the top no matter what the organization. Whether they are paid actually means little in terms of how authority is dispersed (the bigger issue imo).