Been on the receiving end of that behaviour too however I PUG quite a bit, I want to say at least a couple of times a day on one account or another, and my personal experience matches yours: is exceedingly rare.
In fact the overwhelming majority of PUGs are... well, unremarkable.
Don't get me wrong, there have been a few times where I have fallen into the 'something should be done about this' mindset when something remarkable happened that frustrated me however on second thought I always reached the conclusion that it just wasn't severe enough or prevalent enough to warrant any further action.