My new client scope has been too small to be much of a sample yet, but I definitely do not go into prospective clients thinking things have to just be tossed and replaced. I have said many times to clients, "this is not how I would do it, but it is a valid way to do it."
No question that part of being good at that has to be accepting that there are many ways to skin the cat and just because it isn't your preferred approach does not mean that it is wrong. Maybe it is even better. Everyone tends to have certain products and approaches that they will use if not given some reason not to. That might be installing Active Directory or it might be using Cisco routers or maybe installing CCleaner on every desktop. All valid options, but are they the best in every case?