How surprising that some sound engineers can do a wonderful job in a difficult venue and others (and some bands) can be relied on to produce sound that is quite simply TOO LOUD. Too difficult to understand? I do have a small PA rig by the way. I rescued it from a skip and mended the electronics!
The point about competent sound engineering is that you don't notice it - the sound is just right, volume, mix of frequencies etc.
I make a point of praising bands and engineers when I consider it is due and criticising when the dolts produce sound so loud it is painful and in halls where I know perfectly well that more competent people can get it just right.
My comments stand.
Sidmouth just seems to have a particlar problem.