There is a study that asked crowdsourced workers to rate the violence of Legos (and I won’t get in to my personal viewpoint on this research) and used workers from Crowdflower.
Their rationale for using Crowdflower: they used MTurk rationale to rationalize using Crowdflower. Which makes no sense. And seems kind of lazy.
Citation: Bartneck C, Min Ser Q, Moltchanova E, Smithies J, Harrington E (2016) Have LEGO Products Become More Violent? PLoS ONE 11(5): e0155401. doi:10.1371/journal.pone.0155401