@Guy: yes, most developers and even agencies reuse at least some of their code from project to project. It depends, though, on the project. If you get a "good deal" on a fixed-price project to develop a website or app, there's a good chance it's cheap because the developer is repurposing old code with a new skin. Very custom and high end projects have this happen less frequently, of course, but we are talking oDesk here.
t's not always a problem, as some developers have libraries of code they reuse between projects that lets then work faster and more efficiently. As long as you're getting the design and functionality you need and you contractually own it, I suppose it can be okay. But do check your agreement with whomever you hire. The biggest pitfall with reused code in my experience is that certain features are difficult or costly to add down the line, caused by shortcomings with reused code that was intended for something completely different.