"No, you're not crazy! I think, too, that HD-650 are way too bright!
Probably given our different hearing there is no absolute "too bright" or "too dull". However, for any sort of meaningful discourse we have to have a measuring stick, and that is always going to be other headphones. The 650 may be too bright for some, but it's anything but bright compared to phones like the K702 and DT880, and of course any Grado. However, the exception may be if there happens to be, say, a resonance between the 650 cups and your ears that disappears with some other phone. Unlikely but possible. Or an out-of-band resonance in FR that your bat ears are picking up. Worthwhile trying something like the K702 to see. I found I couldn't listen to it as there was a metallic colouration like someone hitting an anvil, but since no one's ever mentioned it I have to assume it's peculiar to me. That could be the case with you and the 650s.