I've been wondering about kerning pairs in fonts. There seems to be a lot of variation in the amount of kerning pairs per font. A font like Frutiger LT Std 55 Roman (251 characters) by Linotype has 441 kerning pairs. URW's version of Frutiger, Frutus (Regular 243 characters), has 979 kerning pairs, and Cartogothic Std (349 characters), A free Frutiger version (ripoff?) by FontSite has 4726 kerning pairs. What does this tell me about the quality of these fonts, if anything?
Of course it all comes down to the quality of the kerning itself, but still, would one spot the difference in a normal text setting to have 4000 instead of 400 kerning pairs?
Some fonts like Jos Buivenga's Calluna have more than 50000 kerning pairs, but does this make them any better than fonts that only have a couple hundred pairs? What would you consider to be the minimal amount of kerning pairs for proper text setting?