Why you want more money is pretty much irrelevant. Whether it's because the cost of living in the area is high, you have two kids in college and a sick mother to support, or you need more money to make up for what you will lose to muggings on the subway, just doesn't matter much to the employer. All they care about is how much it will cost to get any particular candidate as compared to the candidate's skills.
When you buy something -- a car, say -- if you see one that costs $15,000 and next to it in the lot another that costs $20,000, how do you decide which to buy? If the cars were very similar, both had the features you want, etc, I presume you'd buy the cheaper one. Suppose the car dealer told you that the company that makes the more expensive one is located in a particularly bad section of Detroit and so they have to pay more to attract qualified people to work there. Would this lead you to say, "Oh, I guess I'll buy the more expensive one, then, because they have a good reason for charging a higher price"? Probably not, right? More likely you'd think, That's not my problem.
Sure, if the company is in a scary neighborhood, this might lead ALL applicants to demand a higher salary, so that you can get away with asking for more.
On the other hand, even though logically, by economic principles, the employer shouldn't care why you want more money, the employer hasn't necessarily thought this through. Bringing up a reason might help, provided that it isn't a reason that makes you look bad. "I need more money to pay for my cocaine addiction" -- probably not. "This will be a long commute and I'll have to pay significant amounts of money for parking" -- maybe so. I'd be hesitant about "this is a bad neighborhood and it makes me afraid". Valid, I guess, but it might be taken as kind of wimpy.