(Click the character infographic to download.)
Mr. Spencer is old. And gross. (Well, apparently those two are basically the same thing to Holden.) Check out our introduction to this poor guy:
The minute I went in, I was sort of sorry I'd come. He was reading The Atlantic Monthly, and there were pills and medicine all over the place, and everything smelled like Vicks Nose Drops. It was pretty depressing. I'm not too crazy about sick people, anyway. What made it even more depressing, old Spencer had on this very sad, ratty old bathrobe that he was probably born in or something. I don't much like to see old guys in their pajamas and bathrobes anyway. (2.3)
He is, however, good for one thing: he introduces us to the way adults (or at the least authority figures) view Holden, and the way he views them in return. What we see is primarily a big lack of understanding. Mr. Spencer can't understand what's wrong with Holden, and he certainly doesn't know how to help him—his only strategy is to lecture Holden about his future.
The problem? Well, the future is the problem. If all Holden has to look forward to is being a boneheaded authority figure like Mr. Spencer, what's the point?