O Snarky One:
Why not share editor names with your clients? When shopping my novel around, my agent told me which editors at which houses, without me asking. I wouldn't have been bothered if she'd left that detail out--just seems like a different style--but I'm wondering what the reason is for not routinely disclosing that info.
But what if a client is going to be at the same conference one of the editors will be attending? Assume, for the purposes of argument, that your client isn't the type to make a total idiot/pest of herself around the editor while at the conference. Would there be a good reason to tell your client that the editor will be there, in case the editor approaches your client to talk to her?
Y'all aren't reading carefully. What I said was "I don't routinely give out editors' names". What I did NOT say was "I don't ever". There's a big difference.
Of course if a client is going to a conference, or a place where they are going to meet editors I brief them fully. Recently I've even dragged their asses to parties to MEET editors. Last year's Bouchercon I gave one of my clients a list of names, physical descriptions and strict instructions to accost each and every one. (Of course I then sold her book to an editor who wasn't even there)
Of course if a client has history with an editor, previous books, contacts yadda yadda, I ask about that, and utilize it.
What I don't do, and what the original poster was asking about, is routinely send a list of which specific editor has rejected something. The amazing thing is NONE of my clients has ever asked (that I can remember..but it is before 9am) for more details.
The reason I do not routinely do this is cause when you start saying "Editor X at Publisher Z rejected this" it personalizes it. Authors tell me all the time (and they believe it too I think) that they don't take rejection of their work personally. Horse hockey. Of COURSE they do. And why not. There isn't anyone else's name on the page (except mine of course). They love their novel and this chowder head at XYZ said no.
Of course, it's NOT personal, and a lot of times it's not about the book at all. So, I routinely don't give out names UNLESS asked, or it's needed. I don't send them routine rejection letters either but if they ask for them, of course I do. The key thing here is that my clients know this BEFORE they sign the contract. I spell it out. Then I ask if that is ok with them. If it's NOT (and this has happened) I recommend they go elsewhere.
The original poster said her agent sliced names off email rejections. I think that's excessive but I stand by my opinion that its NOT a red flag. It is however an indicator of communication style and business practice and it's clear the questioner wasn't happy. That's the real question. Can you live with how your agent works. If you can't, you need a new agent.