The majority of DPS I've tanked for have been great, but there are the odd few that really ruin the experience by being completely blind to enmity. They assume it's ok just to unload everything, which is fine if you're geared worse than I am because chances are I'll get the mob back fairly quickly and we don't have to worry, however you'll every now and then get a relic DPS come along and think they are best because they have a relic, and consequently think they can tank better than you.

People should play a tank job before judging, but they wont. The problem here is with other people's stupidity and the best way to overcome that is to either leave the group if they continue to pull hate (they will have a significantly longer wait time) providing it is actually their fault, or just get the run done as quickly as possible and hope you never meet them again. Best thing to do is avoid Duty Finder all together, but I understand that's not always a possibility.

Also as a last note, Healers can be just as bad as DPS if they don't know what they're doing or don't understand what a tank has to do to cement hate on an enemy. It's all about timing.