Just a couple of things to add to the discussion (from former elder who saw dozens of these letters and wrote some of them):
1. It's amazing how many of these letters are so poorly written that it was almost impossible to figure out if the BOE was making a positive or negative recommendation. In those cases the letters were largely ignored. Otherwise, yes, your reputation preceded you.
2. Even though these letters are "supposed" to be written by the secretary and co-signed by at least one other member of the body (or two, I can't recall), a large number of letters came in with one signature. These usually carried less weight, especially if they were critical or contained TMI (too much information) because some elder would point out the procedural violation and the letter's message would be discounted.
3. Knowing that these letters are routine is knowledge you can use when doing your fade. For example, we told our secretary we were moving and asked him to send a letter to the new congo. And he did. WT procedure states that the new congo is supposed to request a letter from the old, after you show up at the new location, but many elders take a shortcut here. So a month later the new congo's secretary called up and asked if there was some mistake as they had not seen us at their KH, I asked if the letter didn't mention some serious health problems. He thought about it and said, "Yeah, I think it did mention that." So I gilded that lily and painted a picture of hard-to-diagnose chronic illness for which we were under a doctor's care and let him jump to the conclusion that it was the reason we hadn't gotten to a meeting. I assured him that when we improved, we fully intended to be there.
However, I was wrong; we did "improve" but we never went. And, as expected, neither congo wanted the responsibility to follow up so no one ever did.