I'd say, How much work are they asking you to do?
I saw a job ad once that said they wanted applicants to develop a complete system meeting specs to be found on their web site. The system went way beyond a simple quiz, it was like a dozen data entry screens, a bunch of reports, and a non-trivial database. They also said they expected complete documentation. It looked to me that to do a quality job on such a project was a week or two worth of work. I'm not sure if this was literally a scam, that they were trying to get someone to develop a system that they needed for free under the guise of it being a job application, or if they really thought this was a reasonable thing to ask of job applicants.
I passed it up on the reasoning that, if this was, say, 40 hours worth of work, that it would be a more effective use of my time to spend 40 hours looking for other want ads and filling out less time-consuming applications. I could surely find and apply to a dozen or more jobs in 40 hours, rather than devoting that much time to this one, with no idea if this would even get me as far as an interview.
If you look at what they're asking and you figure you could throw this together in an hour or two, than if the job looks interesting it might well be worth the effort. If they're asking you to do weeks worth of development work before they'll even grant you an interview, I'd just pass on it.
(a) It might be a scam to get you to do development work for them without being paid. (b) Even if it's not a scam, is it worth the effort, or would you be better to spend your time pursuing other leads. (c) If they're asking for an unreasonable amount of work when you're applying for the job, what will their demands be if you get the job?