Probably a noob question, but here goes..
I have a decent pile of disks with games, demos, etc. some work some don't.
- what's the best way to check if a game/disc that doesn't work is just corrupt and can be formatted to be reused of if it just get trashed?
- what's the best tool to format them?
The Format tool. Try re-formatting a disk a few times before you give up. Also, there are format tools which will format bad disks - have a look on Aminet for those. Of course, they won't magically format bad disks, the trade off is you loose some KB of capacity depending on the extent of the disk damage.