I was the Election Judge for the Dem side for 4 Pcts in the N. Dallas suburbs. We voted ~750 people on 2 machines ! I know for certain many of my GOP neighbors were voting with a gleam in their eye and sniping/whispering that they were "spoiling" our results. I didn't know what they were up to until this AM when I saw the results. There was clearly was enough GOP HRC crossover to affect the primary count. I ball park estimate 50 folks out of the total were there for this reason. There was no exit polling and there is no way to know with any accuracy.
This is anecdotal and as someone with research experience I am aware my opinion is useless, and yet I feel the need to express it anyway.