I don't know if it's that unethical -- I think there are a lot of jobs where if you made a graph of the worload it would look rather spiky -- IE, sometimes you're very busy, but with long idle times in between. Those downtimes are a good opportunity to work on pet projects or learn a new skill for career development. I think most good employers will recognize that if you're otherwise good at what you were hired for.
Sometimes they don't know what they hired you for. As in have no idea how the task should be done and how much time it can possibly take. That can be unethical.
If you have spiky workload and work on fun projects or just learn, I believe that to be fine.
upvote, because while i don't know if it's ethical or not either, that's my situation, although i didn't recognize it as such when i first started.
i've used the "variable workload," justification before (at the suggestion of a manager, in fact), but i think an even better justification is that i've taken a major salary cut compared to my previous cubical-oriented, corporate job. also, i try to spend the extra time developing skills that, while not necessary this week or month, might be useful later.
there was a post a day or two ago about "money is freedom," and while i guess that's true, freedom from money can also be freedom.. or something. i dunno, my reasoning is probably flawed, but i feel like i'm learning a lot, eating well, and pretty alright with my job at the moment. a lot of the original post seems like post-PhD(tum) angst to me.
