I'm kind of a person who hates seeing people do REALLY low DPS. I'm not talking about players that do 30-40K DPS in LFR, At this point i think that's appropriate given the audience that does LFR, and usually there are people who can make up for those. LFR is not that tightly tuned anyway.
I'm talking about the players that are really horrible. I once encountered a fire mage in a Temple of the Jade Serpent hc PuG who was doing 2.5K DPS. No, seriously, he was really doing 2.5K DPS. he had no gems, reforges or enchants, didn't use his level 75 or 90 talents and completely botched up his rotation. he used inferno blast on CD, didn't use combustion, stuff like that. I actually felt so bad for him, I gave him my realID (battletag didn't work for some reason) and spent the next 2 hours after the instance tutoring him on his server, explaining what talents to take, what to use when, reforging and enchanting, and finally doing Arena scenario with him so he could get a better weapon. the result was that his DPS went from 3K DPS to 20K DPS, which I was happy about.
but that was the worst DPS i've ever seen. that DPS would have been great 3 expansions ago, and acceptable 2 expansions ago. but in current content, it's just sad. 20K DPS is still somewhat low, but at least it's not so bad that the instance gets harder because of it.
what was your worst DPS you've seen in MoP?