With every new xpac, everyone's gear gets a reset. In the first few weeks you can assume that almost everyone running dungeons need gear. To speeds things up, I've always gone tank, or healer, and rolled on gear for my spec (so that I can do the heroic dungeons better) and all the DPS gear (raid spec). thanks to LFD you pretty much never see the people again, but I still feel a little guilty.
I was interested in how many people take the noble route and stick to main set rolling first before offspec.
inb4 this is why you run with guildies. We ALL do LFD at some point in our lives.