If "Someone is really really really keen on caves, passionately enjoys caving and has done loads of trips with plenty of variety...." i would consider them a bone fide caver.
If they chose to pay for a guide because they are not in a club and there are access limitations on the cave they wish to visit then i don't see why this should make them any less bone fide.
For example- I am not in a club, I cave with a bunch of both club and non-club cavers, and have done for many years, mainly in Scotland where access is not usually restricted. however if i wish to cave in England where access is more often restricted then i may need to join a club or pay for a guide.
Joining a cub does not make me any more bone fide than i was before and paying for a guide doesn't make me any less so. however it does prove responsibility to the landowner.
If the only access restriction is that i be a bone fide caver then i would expect to be granted access without joining or paying a guide. however restricions are often more stringent than that.