You have strong opinions about what is good traditional jazz and what is bad. I know nothing about music. I can't read music. I never learnt to play an instrument. Can you please explain to me what makes some jazz performances better than others?
Wow! That's a tough question.
So let me say right from the start that appreciating any kind of art is a very personal matter. What pleases me may not please you. And that is just how it should be. So I will answer the question in my own way but shall not be surprised if you hold a completely different opinion.
Knowing about music
First, I don't think it's essential to know a lot about music in order to be stirred by traditional jazz or to feel the excitement that it generates. But it does add a little to the intellectual side of appreciation. For example, if you are listening to a piece made up of several different sections (e.g. Buddy's Habit or Climax Rag), it is satisfying to understand which point in the music the band has reached and to be aware when it modulates into a different key. It also makes it a little more interesting if you know something about the chord progression, no matter what tune the band is playing. In other words, you may appreciate it just a little more if you know about the 'grammar' of the music.
But with or without such knowledge, I think it's possible to distinguish between really well played traditional jazz and the not so good.
At the opposite extreme, it is common enough for good traditional jazz to be played without any rehearsal or preparation. Bring together the right mix of experienced players and a fine concert can occur.
But in general I think the best traditional jazz is produced by bands who rehearse at least occasionally, mainly to discuss their music and clarify their approaches to their repertoire. They should tidy up the trickier moments, ensure they are all using the same tune structure and chord progression and they should agree on any special tune endings. The little bit of extra work put in like that can be appreciated and pays off in a better public performance.
But I accept that bands - in special circumstances - sometimes need amplification. In these cases, it is best if it can be kept to a minimum, for example one microphone for use by the vocalist.
First, as my friend Barrie said to me, the expression 'rhythm section' is relatively modern and misleading. The whole band should think of itself as the rhythm section. But these days when leaders refer to their rhythm section, they mean the part of the band likely to consist of two or three or four players selected from percussion, banjo, guitar, piano, bass [string or brass]. In a good performance, these players will, as the saying goes, 'sound like one man'. They too must listen carefully to each other and to the trumpet, clarinet and trombone. In so many of the elderly British bands I have heard, or watched on YouTube, they certainly do not sound like one man: often the drummer is too loud and his rhythmic patterns are disruptive to what his colleagues seem to be trying to achieve. At least for the brighter and quicker tunes, most of the time the rhythm section in unison should play a pulsating but not too loud four-to-the-bar poom-poom-poom-poom (not um-CHUCK-um-CHUCK). This pumps the front line along and sets the audience's feet tapping. A good drummer drives the band without being loud or exhibitionist and a good pianist subjects his skills (in ensembles) to the need for a steady rhythmic and chordal underpinning of the music.
In performance, most bands include a sequence of 'solo' choruses (normally 32 bars, or even 64 bars) by several of the players in every tune. Often these solos have nothing much of interest to say (they are what Chris Blount would have called 'just a load of notes'), though, if the band has a very good pianist, they give him a rare opportunity to show what he can do. Often solo-takers try to play something stretching to the full their technical skills - showing how clever they are. I suppose this is fair enough if they are technically brilliant. Festival audiences can be counted on to applaud this sort of thing. But my view is that flashy and often raucous solo choruses are not an essential part of good traditional jazz.
Sometimes a rather special chorus contributes to a pleasing performance. For example, a band may try a 'front-line-only' chorus and even better a full-band quiet chorus (just tickling the notes) before turning up the volume for the end of the tune.