Really rarely. As you may have noticed, Bob-Oracne, I have zero plot brain, which makes reading mysteries somewhat difficult ;). I generally find I'm not particularly invested in who-did-what or what-actually-happened. I bounced pretty hard off Sayers, with the exception of Gaudy Night.

On the other hand, I'll read them if I like the characters, which is how I read Sarah Smith, Lindsay Davis, and Janet Evanovich. Though I had a more difficult time getting into the Davis because of the plot-heaviness. I think I tend to like mysteries more when they're combined with other genres, like romance or sff.