www.cdfreaks.com is a great source of information about cd's. a standard cd-r indentifier could tell you what dye type, manufacturer, etc of your cd-r's. it is pretty recognized that taiyo-yuden and kodak, verbatim are the best. CMC magnetics is known for the worst, with ritek a close second, i believe.
i believe Taiyo made TDK's old ones.
also, feurio contains an ATIP viewer, for dye type / manufacturer etc.