Sometimes when I start a new web copy project with a client I will get a pre-existing website that has web copy already on it. When you get the project this way, it usually means they're either going for a re-brand and they're looking for a different voice, or they've decided they're just not happy with what they have.
I find it's easier if I get it without any copy, or pre-existing copy that's going for a re-brand, either will need new copy that's fresh and different. If they're going for a re-brand then they'll probably be going for a whole new website design too, and it's almost as if you're getting a fresh slate on which to create something new. It's going to be a world away from what they have at the moment.
When you're given copy they're just not happy with but can't quite pinpoint why, that's when it gets tricky, because you don't know what you're working with. It feels like a guessing game where you're trying to understand what they want, and then wind up potentially creating something that's way off the mark. Some clients can be vague, and they look to you for the answers, and sometimes it's not going to be easy to draw the answers out of them. If they don't know what they want, how are you going to?
I don't get this problem very often, but when I do I will use the same tactics as I do with new clients, that is encourage a few discovery calls, ask them to fill in a questionnaire with a few carefully crafted questions, and try to flesh out what they think they need, how they envisage their brand taking shape, what should their tone of voice be if it isn't in their current website copy right now? You may have to work that bit harder than with someone who has a clearer idea of where they're headed and where their brand is going, but you might strike lucky.
Sometimes, you can just end up in the same place, because if they don't know, they don't know, and you may have to tell the client to go and have a think about which direction they're headed in and then come back later.
Naturally, I always prefer it when I get a website from scratch, from birth, so you're with it from its inception and work with the client, and if you're really lucky, the web designer too, and you can all work towards the same goal. That's a happy ending, but you don't always get that - and that's what makes doing what I do exciting.
You can't always get what you want the way that you want it, but yes, I much prefer to create web copy from scratch. And yes, the occasional client is going to come along who doesn't have a clue, but if you manage to create something out of very little, there's always going to be that wonderful sense of satisfaction at the end of it. And that's what you should be aiming for.