hey, watch where you're swinging those mixed metaphors... one second we're asking about CD-RW, the next its UDF, then we're back to Orange Book sub II.
make sure we're clear on the distinctions <a href="http://www.cdrfaq.org/faq02.html#S2-2
make sure you have the superdrive patch (if appropriate) and/or firmware updates
sacrifice a chicken
if you're convinced they're coasters and have given up all hope, try the same trick that seems to solve certain non-readable (newfangled rip-protection) music CD's... draw a stripe from center to edge on the bottom surface using a felt marker
if you've got the latest toast, drop the cd in while toast is running... it should allow you to do a get disc info where the finder spins ball
full homer headslap is due if its an RW disc and your struggling mac ain't RW, merely CDR or CD-ROM... dead horse, baby
not enough info to troubleshoot much further.
post a system profiler screenshot of your drive info with devices tabs open if you can. toast disc info too if it allows.