Tangledwood, the list of artists appearing at Cambridge is published well in advance of tickets going on sale. If the line-up doesn't match your definition of "folk" why decide to go there in the first place?

It's a ticket that otherwise would've ended up in the hands of someone who would have apprciated it...

As for the noise (a typical festival crowd enjoying themselves in the usual ways) why not move to a different vantage point where this is not a problem? Easy to do at Cambridge....there are plenty of people listening closely if you move nearer the stage.

Also, you don't say who conducted the mandolin workshop but if (as I suspect) it was being led by Tim O'Brien it's hardly surprising you'd pick up a tip or two!!