After awhile, classical guitar strings go duller than when new, even if you wash them. The basses wear down more quickly than the trebles. A rep from one very well-known manufacturer of classical guitar strings told me that basses generally wear out 2 to 3 times faster than trebles. My own experience is that 4ths wear out most quickly. I speculate - and note, it's just speculation - it's because their windings are more delicate than the other basses and that they're depressed against the harder metal frets more often in much repertoire. There may be other factors, of course.
I've asked various parties whether any strings are marketed on the grounds that, e.g., they last twice as long as the competition. My responses haven't yielded any positive answers. Some have even suggested that that's just too 'subjective' a property to measure - as if the same couldn't be said for timbre, brightness, and other aesthetic properties of string sound.
It seems possible to devise a reasonably good set of empirical trials to test relative durability. So far as I know, none has been tried. Does anyone know (a) whether there are any strings marketed for their relative durability, (b) whether there is any good empirical evidence to account for growing string dullness, and (c) whether there have been any reliable and not merely anecdotal - one's relying merely on personal experience - tests of string durability? This could be a basis for someone's acoustic engineering thesis!
Thanks for your help.