1.cdparanoia has some switches that can make it more verbose.
2.If the errors are effecting the md5sum (it only takes one bit flip to do that!) then either the drives lens is dirty, or, far more likely, the disk is scratched and cdparanoia is guessing.
3.Lens cleaners are sold at Walmart etc.
4.Scratch fillers are too. One emergency scratch filler is the grease from the side of ones nose, we've been using that to reduce negative scratches in the darkroom when developing and printing photographic films since the time of Mathew Brady if not before. I once used it to fill in some of the deeper scratches on a CD I loaned out that came back trashed. It made it playable, where before I greased it, it wasn't. Smear it on the worst damaged area, and polish gently with a cotton swab. Vaselene works too, and is probably cleaner yet. It doesn't usually take very much, if the disk actually looks greasy, waste 2 or 3 cotton balls to clean off the surplus, all you want is what fills the scratch(es).
5.Basing a good rip on the md5sum's consistency is probably being too paranoid, the ear is quite capable of ignoring a flipped bit 99.9% of the time. Data disks are another, completely different horse, with all sorts of error corrections built into the encoding, so they are much better equipt to tolerate a flipped bit than a music disk will ever be. We are so used to data being read flawlessly that we think a music disk should be too.