Pros
Dealing with bad code style. This can give you the skill how to dig deep in a black box project that has no documentation and written badly
Cons
- Project Managers are immature, they don't know anything about software engineering process, they don't know how to write proper requirements and how to write specs. They don't know the concept of releases and phases, THEY DON'T KNOW HOW TO MANAGE AT ALL - Developers doesn't know how to write scalable code, they are dealing with freelancers so the code is written in fragile way and the developers' main interest is to fix to deliver not to fix the main problem. - Front end developers doesn't know how to write robust and scalable code. I saw in many cases that measurements and positions of divs were hard-coded!