I think that the book <=> food analogy is a good one. Most of the time you have a reason why you are eating something... Is it due to a craving, perhaps an area that is lacking in your current diet (I get major salad cravings... and the occasional need for another home repair book).
Some things you choose because deep down you think they are good for you. Other things you spend time experiencing so you have something in common with others to talk about. Some experiences we choose just to broaden our horizons. And sometimes, late at night, we pull our a guilty un redeemable pleasure... while no one is looking.
Some of my greatest regrets / time sinks have been when I have forgotten why I am doing something, and make a choice based on my current status. I have tried to read several Stephen King books for pleasure... and fought way to far into them out of a need for compleateness or fairness. Other times I have kept myself up all night reading about wood jointing
, when all I needed to know what what to look for in a special type of saw for my shopping the next day
...
There are so many wonderful variations in this world that your pleasure reading (and eating) should be pleasant. However sometimes you have to try something new 5-10 times before you gain an appreciation for them... and eventually enjoy them. (for me wine and biographies fit into this group)