Somebody already asked the question. Would you take money from the NSA to feed the poor? If the answer is no, how far do you have to get away from the NSA before you would take such money? I assume that the NSA, like most large organizations, has many sub organizations, some of which probably do radically different things. I suspect that the mathematicians who work for the NSA are not involved with the data collection and were probably ignorant of the data collection until Snowden came along. So I have some sympathy for their plight. But that sympathy only goes so far. NSA is an off-budget secret organization. When have such organizations ever been morally clean? I find it ironic (and hypocritical) that normally severely left of center political types appear to be willing to work for such an organization.
I personally don't think of NSA as evil -- generally those who are given a particular job to do (such as data collection) will do that job with a zeal that pushes them beyond sensible moral limits. Many Law & Order episodes deal with the problems caused by police pushing the bounds of legality in pursuit of a criminal. I don't see those police as evil either -- even if they have broken both moral codes and laws.