Saxophone players The problem here is that they are recruited and trained by other saxophone players. Personality tests shows that they are exhibitionists, first and foremost. Some of them are social contrarians who will play in a scruffy T-shirt with We Love Atlantic City on the front. These people will always play with a very dirty instrument. But a dirty instrument many also be a much loved archeological find. They are taught that their aim in soloing is to play as many different scales as possible at a very fast pace and never to acknowledge that the rhythm section is telling the audience, and them, where the music is in reality. Later on in life, saxophone players realise that they really need to know more about chords and progressions so they buy a small keyboard in order to see the notes. Then they find that there is a lot of mental effort involved in learning about progressions and so on, so they end up playing the blues scale 99.9% of the time.
Trumpeters Trumpeters are nearly always male and are in it only for the sex. If they play loud, and very high they can attract women from miles around. Not for nothing was triple tonguing invented by a trumpeter.
Jazz singers No one in a band can make the musicians change the usual key of the song except a female singer.
If the singer smiles at them and says thank you then the rhythm section will forgive her for not coming in on time, not finding the right note and for talking to the audience while the soloists are playing. Male singers have to stick with the key the music was written in.
Playing simple jazz. The simplest way an amateur can play a jazz solo is to turn down the sound control on the amplifier. Afterwards you should ask if there was something amiss with the sound balance. Experienced amateurs realise that there are seven notes in each scale. (Actually there are eight notes in the diminished scale but only pianists know that.) Players can cut down the amount of notes they have to think about by 28% if they only use the pentatonic scales. (5 notes in each pentatonic scale, saving 2 notes. 2 notes saved out of 7 equals 28%. Music is very mathematical)
Theoretically, you can cut the number of notes used in a solo to four if you just use tetratonic groups. (This is the pentatonic scale minus one note). But very few people know this, and it has never been tried in anger. It is mentioned only by clever dicks who want to get one back on the pianist.
(Actually the chromatic scale has 12 notes in it - but this is so obvious that even Rover Scouts can work it out, and no one can use it for long before being thrown out of the band.)
Jazz teaching Jazz teachers will tell you that there are no bad notes in jazz only "poor" choices. They say that if you can play immediately a semi-tone below or above your bum note you will get out of trouble. In theory this may or may not be true but by the time you've tried it the band has gone ahead with another couple of bars by which time the "corrected note" will now have become a bum note so no one has ever found out. Look behind at the motives of jazz teachers who say this kind of thing. Jazz teachers want you to like them and keep hiring them which is why they tell you this crap. You are their living after all. It is possible to make so many poor choices, that you get thrown out of the band.
Deps This heading is to test you, to see if you know the "in" words in jazz. Band leaders hate it when people can't turn up for the gig. People always claim illness but it is usually because they have got another gig that night which pays a bit more. Sometimes band leaders insist on you providing and rehearsing your own deputy. ("Dep" - see it now?) Never ever bring a dep who is better at playing jazz than you are. Otherwise, in the long run you will have to go back to looking at the small ad cards in musical instrument shops. By the way the yanks don't say dep but sub (substitute) but that could be confused with tritone sub so stick with the English.
Avoiding copyright fees No copyright exists if you wait 70 years after the death of the last surviving composer. You can bring this event forward by several years if you let the composer hear you improvising on his music. Jerome Kern hated jazz.