Is there really a need to denigrate a whole genre of music and musicians just because you may not care for them?
I think not.
Would anyone like to get this thread back on track?
Sure, I'll give it a go. How about contrasting the improvisation of jazzers vs. classical.
When Jazz players improvise it is usually a solo over the changes. Classical players will think, what the heck does that mean? The answer is that songs (the great American songbook?) typically consist of a melody and chord progression. The art of jazz improvisation is more often that not (at least 95% of the time) embellishing these melodies and extending the harmony of an existing song. The song could be My Favorite Things, Love Supreme or Somewhere Over the Rainbow, the point is to keep it somewhat recognizable and then go farther and be a bit virtuosic while doing it. Classical players would call this improvising variations, but since this is what jazzers do almost exclusively they just call it improvising.
As just mentioned classical players when improvising may do variations on an existing theme (or song), or they may take a theme and treat it within a classical form, fugue, sonata, rondo or variations. But usually it's none of the above, they're playing off the top of their head and making up a piece from pure imagination.
The downfall of these approaches.
Jazz players can easily improvise badly (especially if they're not good players). The temptation for the good players is to get lost in virtuosity and forget about making music. This is when improvisation descends into "note spray."
Classical improvisers have the same problem, except that they;'re responsible for everything, which means more can be bad. The theme may be insipid, they may not have a wide harmonic lexicon, or they may forget their sense of taste (good judgment) and finally the lure of virtuosity is as much a risk for classical improvisers as for jazz players.