I think you're right. Roll off is an arc shape to the response, getting lower and lower till it disappears, and recessed means lower than the rest of the spectrum, but still flat and extended. I think rolled off is actually a term that probably applies more to modern headphone's bass response than treble, because headphones these days extend way beyond what we can hear in the treble. A least that's my understanding.
Saying that a headphone has rolled off treble doesn't just say that it is warm sounding, or has less treble levels than you'd like, it also suggests that it is unable to produce the highest frequencies. Not that I use all the right terms or anything because I certainly don't, but this is what causes the hubub in the LCD-2 threads.
Edited by rhythmdevils - 5/15/11 at 2:19am