I think there is some confusion here as to what a "good" rom actually is. I define a good rom as one that has been unaltered from its initial release. A bad checksum does not mean the rom is bad. Some roms are betas/unreleased versions that were never actually released on a cartridge. Some roms are suppose to have bad ckecksums and it is the ones with the corrected checksums that are the hacks. The roms with the (!) are "good" roms, as they are verified. So any rom without the (!) could potentially be "bad". I find it doubtful Nach (or his friends) have actually verified every single cartridge (including the prototypes, betas, and compiled images). There is no such thing as the perfect romset, so people should delete those all those rom sets and only download those games they wish to play (If it is impossible for them to obtain them in real life).