I have, almost without exception, really enjoyed working with every textbook publisher salesman that has visited our campus.
Even though the job of these reps is to make the sale, many of the companies send their reps to our department to visit regardless of whether we are currently using any of their books. They'll be visiting even if there's not a prospect of us using one of their books for several years.
Another thing I appreciate is that I've found most textbook reps are quite interested in teaching. They want to know how we instructors are teaching, what our challenges are. They often have very thoughtful things to say about the thought and design process that went into a book that are not immediately obvious.
Textbook reps have a very unique perspective on the state of teaching. They are probably among the few people who go from institution to institution and actually talk to different instructors about their teaching.
It does not hurt that when they are here, they often feed us lunch if they think there's a sale to be made. And even when there isn't, they'll often bring cookies.