| since it is a 12v field battery, I would never be afraid of trying it out | charge it up and use it, if it won't work throw it away | there is really no risk factor associated with this battery
Yes, that is true -- since it's not going in your plane, a failure of this battery will not crash your plane, so it's not such a big deal. Though it's failure might mean you can't start your plane, which would be a bummer. Test it at home, not at the field. Outside though -- they can vent hydrogen.
This sort of battery (lead acid, or gel cell) tends to self-discharge very slowly, often holding a signifigant charge for many months (even a year or more?) -- which is good. But once they are discharged, they slowly ruin themselves. That's what will destroy them -- not so much time, but being left discharged for any period of time.
If the battery is dead (not charged) now, it's probably ruined. If not, it's probably ok. In the former case, you can try to charge it and it's possible it'll come back, and some people have had luck hitting them with (slightly) higher than normal voltages to bring them back to life, but I've never had much success there.