<<I failed basic, but I passed the book work, and my fail was a very subjective one, based primarily, I felt, on character judgements rather than ability.>>
But the character side is immensely important. At Heathrow back in the old days, when a controller was approaching validation standard the training officers would ask: "Is he/she safe and can I work with him/her". If the answer to either was "no", validation would be delayed or even cancelled. In busy ATC units everyone depends on everyone else so people have to be capable of working with a team, rather than as an individual.. They might appear to be very good, but will they stand up to immense pressure under busy situations? These factors have to be considered.
Do remember that those judging you are very experienced controllers and they'll know whether somebody has the right attitude and will "fit in".
If I have misunderstood what you meant I'm sorry, but hope you get the picture.