I spend quite some time educating my clients, especially the business clients. They know all about their profit and loss reports, and I show them the M-1 as where their books, that they understand to the penny, meet their tax return - which loses its mystery once they are shown the "book to tax" adjustments.
I think a big problem with crappy tax preparers might start with them taking on more decision making than is even remotely wise. Clients don't pay us to make their decisions, they pay us to explain and ask the right questions. We really should charge more money