Jonathan--the only thing I would quibble with is that it really is essential to clean the LPs thoroughly, both for sonics and to avoid extra stylus wear.
Mono cartridge classification
While researching various mono cartridges I notice that Ortofon makes specific reference to the cartridge (their SPU cartridges anyway) being best suited for playback of certain mono recordings. I don't recall seeing this mentioned for other manufacturers. These references are given in the form of a number (25 or 65 is what I've seen) followed immediately by a symbol that looks like a stylized letter "n" and then the letter "m". What does this symbol/abbreviation mean? How do I know which of these a certain recording is in? and I'm assuming its not that important to worry about since I don't see it mentioned by other manufacturers - or is it?