I use EAC for disc ripping, and if you get no errors in secure mode, or an Accurip "accurately ripped" score, they are perfect with no possible improvement. Sometimes for bad discs, secure mode comes to nearly a standstill, and the (eventual) results aren't really worth the wait. In those cases, I've used burst mode with better success, but only for those tracks that are truly stuck. EAC will tell you those sections that are questionable, so you can listen to them or view them with a WAV editor to see how bad it is. Sometimes you just can't tell there were errors and you can listen to them as is; sometimes it's worthwhile to rescue the audio by snipping out bad samples. And sometimes it's a lost cause and you should replace the disc. (Some libraries have surprisingly thorough collections. Technically piracy? I suppose, but if you're archiving a disc you already own I could make the case that it's at least morally defensible. DON'T do this if you don't already own that exact title or you're ripping off the artist.)
Also consider using CUEtools, which contains a free utility for repairing slightly damaged audio files. It performs a checksum analysis of your files and compares them to perfect copies. If some are only barely damaged, it'll use the checksum data to repair them to perfect condition. I use it as a matter of course to verify all my audio files, which mostly don't need repairing.