[RogerL]

You will find this sort of thing in big and small companies, and find really good practices in both big and small companies. You will find tiny companies (< 20 engineers) with no code review, no unit tests, long lists of unfixed bugs, a resistance to source control not spelled "svn", broken custom written solutions when there are excellent open source or low cost alternatives, people that won't talk to each other, and so on.

In general I'd say you have a greater chance of changing things in a small company. But really, don't judge by company size but by the groups you talk to. Learn to interview better. Ask them about the workflow. Ask to see the code base. Ask about the balance of process vs pragmatism. Ask about the challenges (both in terms of interesting work, and then annoying stuff you deal with). If you seem to have it together more than the majority of people that you talk with, run away. If you don't think you can learn from them, run away. If you find yourself thinking "man, I'm really going to have to step up my game" take the offer.