In reply to twsjonathan.

It's true that not all are bad. However, there's really no way for prospective buyers to know this up front at the moment. It's not really a question that most of them even know to ask, nor should they have to.

And, just because a plugin is used doesn't necessarily mean that the problem is fixed. I've seen many authors there with custom one-off plugins that will only ever work with one theme, so it kind of defeats the purpose of separating the code in the first place.