What's the line of legit vs shady in outsourcing?

Outsourcing tin beryllium rather legit. Sometimes a customer want to springiness nan full task to personification other to grip nan hiring and value assurance. But nan accustomed presumption is that nan customer knows nan freelancer is outsourcing.

It's besides possibly communal for freelancers/independent contractors to outsource projects (or a nasty portion of nan project) they don't want to do aliases they are excessively engaged to do them. There are stories for illustration that, but they don't specify if they person informed their clients.

On nan different hand, immoderate clients ne'er expect their hires to outsource to others. They want nan activity to beryllium done by nan personification they hired. Some mightiness garbage to salary nan freelancer erstwhile they find retired that nan activity is being subcontracted.

Is location a statement betwixt outsourcing being legit versus shady? Are freelancers/independent contractors legally required to pass their clients that they are outsourcing?