So, when might you consider turning down a job offer. Well, that's really up to you to decide. It is certainly a tough and important decision that only you can make after consulting with friends, family, and industry mentors. However, here's a few examples of where you might be better off waiting for something better.
Let's begin with the most obvious here. Just because you're feeling desperate, you shouldn't get involved with something where you gut instinct tells you things aren't right. Keep alert and avoid falling into traps for which the unemployed are particularly vulnerable: very low paying jobs that should be much higher, scam emails attempting to steal your identity, etc.
Cost of Living
Any salary is better than no salary at all, right? Not always. Let's say, for instance, you're currently living a very low-cost life. Maybe you saved up some money, moved in with family in a small town, and are using those saving only for expenses that are absolutely necessary. Your cost of living is currently very low and you could, in theory, continue to live this way if needed. Now, you get offered a job in Los Angeles, or any other major city. It isn't your dream job and the pay is questionable as far as the ability to live off of it in such an expensive place. In this case, taking a job with a salary that won't meet even your most basic of needs (1 bag of Ramen noodles a day is not a healthy diet) will actually cause you to eat further into your savings and possibly even compile high credit card bills just to cover the costs of rent, food, and healthcare. If this job means you won't even be able to make ends meet, but you're doing okay as is, you might want to consider whether or not it is the right choice for you.
Lack of Interest (At All)
As previously mentioned, you should be willing stretch the range of what kind of job you are willing to take. Maybe you want to work in music marketing but have decided that any job in marketing is acceptable. That doesn't mean you should have to take a job in finance just because it is a job. Perhaps your goal is to work at a concert venue, but have decided you would be willing to take any job involving live events or event planning. So, that doesn't mean you should have to take a job in a doctor's office. If you're going to be completely miserable at work doing something you seriously abhor, you might be better off putting on that time that would be on the job into finding something at least somewhat in line with your interests.
The moral of the story: you don't have to take a job that will make you miserable. Yes, you want to get back into the work force as soon as possible and stop feeling like a useless bum, but sometimes you need to be willing to stand up for yourself and admit that you deserve better despite the fact that the economy is tough. Keep working towards your goals, don't give up, and find a way to turn unemployment into something positive (volunteer, learn something new, start a website, etc. ). Eventually, you will find something that fits and, when you do, you will be glad you didn't settle.