I have had several talks lately with students considering graduate school. All of these students are pretty savvy, and I can tell when I start in with the spiel about the job market, etc., that this is not the first time they've heard of such a thing. Some of them have decided not to apply for next year, after all.
More awkward is the case of a student applying for a program in Not My Field, who nonetheless asked me for a letter. There is no major in Not My Field here at Small College (I doubt there is at very many small colleges, in fact); student has, I think, a double major in history and Field Related to Not My Field. So I've agreed to write the letter, and I can talk about the student's general intellectual qualities and work ethic, but it's definitely harder to talk with confidence about what the student can contribute to NMF, since I don't know it that well. I also worry that the student is operating at a disadvantage without a major in NMF--the student also seems pretty nervous. So I'll just write the best letter I can, and try to consult with student about a plan B if things don't go as hoped.