An interesting discussion in the post and comments about whether short term incarceration works.
My experience is that for a significant portion of my clients jail terms are just part of life. While it doesn't happen often, I've had more than one client who wanted to serve time rather than get a large fine - usually they are not scared of jail and pretty clear headed: "I either do some time now or I get a fine, can't pay it, and do the time later (and still owe the fine)." I've also represented your basic homeless guy who commits a minor crime so that he has a roof, bed, and meals during the winter.
When these clients do get upset it is usually because they are going to lose their job. Mind you, I'm not saying that clients like going to jail. I'm just saying that for a number of them it's just another of life's inconveniences.
Now, the people who are from a fairly standard middle class background get scared half to death when they first go to jail. I'm a big believer that these folks shouldn't spend too long in jail - maybe a week, at most two. If they are in the jail for a short period of time there is a good chance they will be "scared straight." However, if they are there for long enough to acclimatize they realize that it's not really all that bad. Books to read, television to watch, basketball to play, meals brought to your cell, and all those fears about what the other inmates will do to you aren't coming true. Eventually, the worst problem becomes simple boredom. At this point jail becomes useless.