At Head-Fi there's this idea that you can always get something better. Whatever your crazy tastes are, there's always another headphone out there that will make music sound better than what you have now, until (theoretically) you work yourself up to a TOTL system with a $2000 amp and who-knows-what-else.
It's this mentality that drives many of us (maybe just me) to go out and try new headphones, even if that entails selling my previous headphones, even those I like a lot. And why not, as there's the excitement of trying something new and you can minimize financial losses by dealing on the used market. Btw, kudos to the FS/FT forum here, I've never had a bad experience and it's the only reason I can pursue this hobby on a college student budget.
BUT after 2+ years of doing this, and trying dozens of new models based on forum advice and reviews, I realize there are some headphones that really stick to you... The sound just seems right. Maybe they fit perfectly on your head. I don't know. And after trying some of the more expensive, higher-end offerings, like the HD800, T1, HE500, D7000, W3000ANV, I simply do not prefer them over my older, cheaper, more-ridiculed, less technically-capable headphones. So I'm going back to collecting all those headphones that I really liked in the past, like the DT990, HFI-2400, W5000, and K701 (my third pair).
TL;DR: If you have a headphone right now that you like a lot, but then you read all the crap they get on head-fi and you wonder if something twice as expensive will be better, well, 1. that's not necessarily the case and 2. if you've unfortunately convinced yourself that your current headphones are bad and you need to upgrade, well, use the FS/FT forums here, they are awesome.