I have managed to use grep to be able to tell if an .hfe file has bad sectors or not (looking for "CRC ERROR" or something close to that). However, I have not found a way to reliably tell if a .scp file has bad sectors.
(PS: It would be really nice if hxcfe, in the presence of a -conv: parameter, would set a condition code: 0 if the conversion was successful, and a 1 if the conversion encountered bad /missing sectors.)