There is such a thing as bad farming practice.Nope. Not at a policy level anyway.
For sure, farmers can discuss/ argue among themselves about whether they think that their system is 'good' or 'bad'. You wont find me having those discussions. Having direct experience of farming at both ends of the (supposed) eco-spectrum, combined with an understanding of the real environmental issues along all links of the food chain, I am adamant in my belief that there is no such thing as 'good' or 'bad' systems. But if farmers want to willy wave, crack on.
However, that's irrelevant to ELMS. ELMS is about Govt policy, not individual farmers views, and at a policy level there should be absolutely no attempt to distinguish between 'good' and 'bad'. Witness the pickle that trying to do so has got Defra into.