I have a '67 Coronado II and it is a fine bass. Decent playability and a good, hollow-body sound. Maybe mine is an anomaly, or the few you played were unusually bad specimens.
JMJ has played one and a few other studio guys I can't think of have used them from time to time. It is probably not a sound you want for most genres or all the time, but that doesn't mean it is worthless.
I owned a '67 for two years; hardly ever used it. The setup was such that it was seemingly impossible to get the notes above fret 12 on E and A to not fret out due to them smacking into the neck pickup.
It is definitely a one-trick pony. I liked the sound though.
