Mulberry, many bands were renowned for bootleg recordings and were often of excellent sound quality... I think Ya Ya's was released on the strength that Live'r Than You'll Ever Be was doing very well in sales and was NO.1 / book of the month in the boot charts.
Often studio staff leaked outtakes or stuff from original masters... if reproduced many times, then the sound quality suffered... I have yet to track down a clean copy of Shades Of Orange... which in itself is a great number.... but demo it is and... it shows. Punters in the audience were often cheeky enough to stand there with a Bush Recorder... but handclaps and screams weren't Mick's... but some chick showing her rack next door!
If Jagger had two mic's gaffer taped together, you knew that it wasn't just for the Green Room playback later.
In recent years the interwebs has unearthed many rough mixes and demo takes.. shame the record shops as a whole never took up the baton.