I don't see it as being about 'good' per se. It's about being true to your own set of ethics, which is much more important when it comes to building a reliable reputation that will get you hired. Becoming known as a psychopath who'll kill anyone for the right price and is indiscriminate about bystander casualties will get you runs, but generally the sort where Mr. J doesn't much care if you survive to get paid. It makes you disposable, and as much a threat to your employers as to their targets.
This is part of what I wanted to say with the oneliner, yes.
People with a specialization that simply doesn't lend itself to wetwork (a hacker e.g. would often be hard-pressed, although you can always get creative, of course) or a firm conviction about the kind of jobs they do, are not necessarily too weak or too nice to run the shadows. They can still be ruthless individuals, ruining lives instead of taking them, for the right amount of money, or simply as a side-effect.
Just having your code of "no wetwork specifically, thanks" doesn't mean a lack of skill, squeamishness, or unwillingness for getting your hands dirty. Quite differently, it can help building a reputation of someone who gets certain jobs very well done, instead of being a jack of all trades, master of none. It also doesn't need to mean that you are too high and mighty to take every job you're offered. It simply means that you're an independent operator who is very well capable of knowing what you can do and, above all, independent enough to pick and choose your jobs.
Every idiot with a gun (and a lot of them even without one) can kill people, but it takes a special skillset to become a successful shadowrunner.