I make web applications for a living working from home.
Sometimes a client pick a technology stack that is likely to hurt the project (severely over-engineered, bad combination of components or just the wrong set of tools for the task).
The cynical may think: bad choices for the client are not necessarily a bad deal for you, aren't you charging by hour?
However this is a tough spot when you operate over online freelancer markets like oDesk/Elance, because a disaster project is likely to get you a bad review and hurt your reputation, even if it is not your fault.
My dad used to say that either you have the customer or have the reason; how do you talk sense into a client that made wrong choices for the project?