Well, if you're REALLY concerned about having legal title to all the games you play, you could always purchase the game from Ebay and if the disks are corrupt, you could then download the (illegal) ADF, and use it legally (since you have proof of purchase of the original software by owning the physical package & disks).
I also recal that there was a site hosting Amiga games legally available for download (had been released by their original publishers/authors).
