I've only heard them on new pads in the shop - and still compared to neutral stuff like DT880 (sorry for hammering on about the same headphone - it's just an example) I still feel that's the kind of sound it presents.
Conversely, one who is indeed accustomed/adjusted to the HD600 would consider the DT880 a bright headphone and be put off by the comparatively forward treble presentation.
As a disclaimer, I do actually prefer the overall sound presentation of the HD600 over the DT880 - there is no hate for the Sennheiser here whatsoever.
I actually encountered people who didn't like the new pads because they're too bright for them and not enough bass. Old pads for me brings out the micro flaws that ruin the sound for me. Overall, tonally it seems warmer, but if one really pays attention (which is no problem for me because when I listen to my reference system, I really just listen), the notes are unnatural. Bass seems to hit hard, but actually the lowest range is just too loud, the decay is kind of bloated already. High frequencies have a spike that seems disconnected from the midrange, which is warm, then you get a sharp cymbal note. Ouch.
The nice thing about the DT880, however limited experience with it, is that it puts the vocals a bit more forward. The HD600 (good pads of course), instead of "(too) warm" I perceive it more as "too flat," in terms of 2D staging but also the relative non-emphasis on anything (especially vs Grado for example). Overall however I preferred this "too flat" tonality, even with the soundstage considered, over a bunch of other headphones in its price range. The K701 was my second choice, but if the pads had that much to do with the HD600's sound, how much more earpads that are thicker on one side and cost $30 more per pair? Didn't gamble and went for the HD600, which I've wanted ever since it came out while I was in high school. Unfortunately I got distracted by speakers along the way before I conceded I should build my own house first, or stick to headphones