I have a policy that ANY potential client for a domain I value above 10k has to fill out my form at: inquiry.mapledots.ca
The form specifically specifies the information provided must be that of the end user, yet broker after broker fills it out with their information.
I respond by telling the broker they are welcome to negotiate on behalf of their client but I will not be engaging until both parties understand who is at the negotiating table.
I had an inquiry from Dubai and the broker said the client wants to remain anonymous and is willing to pay 10k over asking price to stay anonymous. I responded that it does not work that way and some of my domains are targeted at larger corporations who would have to pay according to their global reach and net worth.
I do the same for my higher value .ca's and recently had an inquiry from a new startup who refused to identify themselves. I had the exact match domain and told them to add a second word to their name until they were confident to negotiate in good faith. The broker kept pushing me until I quoted a higher price because it was a blind negotiation. I was then told it was too high a number and I should consider a lower price to which I responded that I will not consider the conversation the start of a legitimate negotiation until I know who the end user is.
Even on platforms like SAW and DomainEasy I ask the seller to fill in my form once they want to start negotiating price.
Domains I value under 10k will usually get a BIN so its not a problem, but I find it difficult to deal with brokers, and almost everyone says they are a broker trying to keep the client confidential. Well I really don't care that the client wants to be confidential and I tell the brokers straight out that I do not do blind negotiations on my higher value domains.