taking such spaghetti projects is profitable. Adding to spaghetti is not too hard. The customers are asking for it – hence its not unethical. These customers have already proven they don’t care about the internals. And then spaghetti also has patterns within – making it easier to understand as we spend more time with it.
Second, these projects are extremely frustrating. We know what’s wrong, but voluntarily decided to live with the wrongdoings of other developer(s). Of course we get paid well.