This is very timely. I have been thinking about starting a thread titled: Authenticating the Authenticators
I have used Carol Ives' service for authentication in the past (caroldiva.com), but I don't think she is an expert on all brands.
I knew about Etinceler, and also Fake Spotters, Castira, and Delortae, although none actually identify who is behind the organization except Carol, who operates alone. (I hope at this point in time everyone knows NOT to use My Poupette!!!)
What concerns me is potential conflict of interest, i.e., authenticators who authenticate but also sell pre-loved bags. If the organization has several or many members who are sellers, then the potential exists for conflict of interest and potential for less than due diligence in authenticating it's members wares. I would like to see transparency in these organizations and for that matter, transparency anywhere authentications take place.
Potential certainly doesn't automatically translate to unethical, but just like an eBay seller who advertises themself as a tPF member, they should be prepared to be transparent about their identity and re-seller status if applicable.
I started thinking about this because of some research I'm doing now on an eBay seller.