I assume this thread will generate copious replies, so I'll be short:
In general I think we tend to exaggerate differences in equipment from what we're used to. When something is tad bit better than what where used to, we exaggerate it as huge. Similarly, when something is a bit worse than what we're used to, we exaggerate it as being worse than it is.
Part of the reason for this hyperbolic tendency is that during reviews you are intentionally screening for deviations from the norm...deviations you probably wouldn't noticed if you were simply enjoying the music.
Most of us, I think, have experienced the phenomenom of buying a phone we think is great, writing great things about it, only to grow bored with it later on. We get used to sound, it becomes our new reference, so if no longer sees as phenomenomal. Then when you try your previous favorite phone, it no longer sounds that great in comparison. You wonder how you could have ever liked it.
Similarly, if you have bought a phone that you think you hate, you may find yourself growing used to the sound and no longer having as ill thoughts about it after getting used to it. Then when you hear a phone you previously liked, that phone will sound really really fantasic, untill you grow used to it.
What I'm trying to get at is that we notice deviations from what we're used to. This extrasensitivity to small deviations causes us to unfairly praise or pan certain headphones.
This is where I get opinionated: I've been a member here for over 8 years. I've kept silent on a certain opinion which I will now reveal. In general I think HeadFi members spend too much on equipment, chasing ever smaller and smaller deviations from the norm. Of course you grow used to the deviations, so you buy more and more equipment to get your next fix.
I own a Stax system and a JVC DX1000. They now gather dust (at least metaphorically, I keep them clean). My day to day headphone is the Sennheiser HD20, which I bought for $20 at B&H. It fits my lifestyle better, and it gives me all the enjoyment of my more expensive phones. This wasn't my first downgrade - I first downgraded from the Stax to the $169 Ultrasone DJ1s. Again, I didn't really miss anything. In general, I think $20 is all you really need. Ya, the HD20 isn't perfect, but unless you are constantly listening to better phones you won't miss anything in the long run. And better phones will still sound special to you when you occasionally come across them.
I think HeadFi does new members a disservice by encouraging them to buy gear they don't really need to enjoy there music on a day to day basis. Really folks, a $20 pair of HD20s is all you need. If you want to buy more expensive gear because you love the hobby, or love the novelty, then sure buy it...but don't make it sound to newbies that they can't hear their music "correctly" without an amp or more expensive gear. The difference between a pair of stock headphones and an HD20 is 10,000x greater than the difference between an HD20 and an HD600 with proper amp. Besides, you'll simply grow used to the HD600 and a proper amp and it will cease to be special.
Which reminds me, I really need to review the HD20s....