Is it useful if students read a paper or two written by a department seminar speaker prior to the speaker's talk? Are seminar-focused classes successful in their goal of getting students more involved and interested in seminar talks?
I have never taken or taught a course that was focused on getting students more involved in a speaker series, but I have given talks at many places that do this. My view of this topic is therefore an indirect one.
In cases where I have the opportunity to interact with some of the students who have read a few of my papers in advance of a seminar, I have asked the students whether they thought such paper-reading and accompanying discussion was overall useful. I make it clear that I am not asking them if they liked my specific papers and talk but am asking whether they find that the seminar-focused class is successful in its intended general goal.
I haven't kept track of the responses in any systematic way but my impression is that these seminar-focused classes do help some students be more interested in and get more out of the seminars, but that, at the graduate level, many students don't like these classes and don't think they are a good use of their time.
At the undergraduate level, students tend to be more positive. In that case, discussing a speaker's research before the talk might be the difference between understanding something and understanding nothing. At the graduate level, however, students tend to feel that their time might be better spent on other activities.
I think it must be difficult for one faculty member to handle such a course, but a team-taught course in which various faculty cycle in to help discuss papers/seminars in their field of expertise could easily end up being disorganized. From my limited database of anecdotal experiences, I tentatively conclude that these courses are well-intentioned but are difficult to implement in an effective way.
In some cases when I visit a university with a seminar-focused class, I am asked to recommend the paper(s) the students will read in advance of my visit. I always have a hard time with this because if I have published something, it is by definition old research already, and mostly I want to talk about my new work. I do try to mix old and new in my talks, using published work as a basis to discuss more recent and ongoing work, so in some cases it is possible to recommend a paper that is somewhat relevant.
In other cases it is more difficult. I have had students say to me after a talk "I wish you had talked more about what was in the paper we read." I can see their point, but why would I want to give a talk that was entirely composed of work that is already published? I might as well just stand there and read one of my papers to the audience. I like it better when the students or faculty choose which paper(s) to read because then I don't feel quite so responsible for disappointing them by not focusing specifically on that/those papers.
An even better situation (from my perspective anyway) is when students who are doing research in a field similar to mine read one or more of my papers, either in a class or in a research group meeting. These students don't tend to want or expect me to repeat whatever was in the paper(s) they read, and so are interested in new material. I've had some great discussions with students who have done this type of pre-talk paper reading.
For students not in my field of research, I hope that I give enough of a general introduction and conclusion, with various mid-talks attempts at highlighting the main points, so that even someone unfamiliar with my research topics will still get something out of the talk. If I succeed at that (and I'm not sure I do in every case), then the talk will have accomplished something whether or not students have read any of my papers.