A bad idea in what sense? Working conditions and pay will likely be good. What you're working on and what you're contributing to help support may or may not be.

A bad idea in what sense? Working conditions and pay will likely be good. What you're working on and what you're contributing to help support may or may not be. Other people can't supply your moral judgments for you. Some people think Facebook is immoral, others think it's great. Try to reason for yourself about what problems you have with Facebook and whether you want to support them.