I tend toward a different type of disposable hobby than Bantik's. I vaguely focus on a subject for a long period of time, sometimes years. My hobbies are disposable in the sense that I treat them as though they were worthy of being thrown out, rather than using them up and actually throwing them out. I don't explore things, even things that are interesting to me, in the depth they deserve. I'm only recently realizing that I've been living this way, but I think I've been doing it my whole life.
I decided sometime around the beginning of high school that I wanted to play the guitar. I took lessons during most of high school. I've earned some respect among my college buddies for my guitar skillz. However, my playing is sloppy. I've got talent, and I think that may be what let me get by without practicing all that much. Consequently, I can't recall the details of a lot of the things I was taught--scales, speed exercises, notation, chord voicings, etc. Since the guitar was my hobby I should also have paid more attention to all the types of guitar and what guitarists know about them. I can tell a Telecaster from a Strat from a Les Paul, but I couldn't tell you what makes their sounds different or how they're made or how to care for them besides changing the strings and not bashing things with them. I don't know what I should about the great guitarists. I was probably pursuing another disposable hobby when I should have been practicing.
That was a typical hobby for me. My approach to hobbies is an extension of how I approach life: passively. As a result, I'm not an expert or master at anything. It wastes a most of my potential, and believe me I've got a lot.