I have this problem less with better drummers who hit stuff how they want it to sound (well duh).

But it's either a slab of cardboard between the hat and snare if it will fit or sample replace/augment the drum for me.

It has less to do with volume (drummers hitting too damn hard) and more to do with the high pitch of the hi-hats, I think. They simply cut through everything a lot more clearly.

But yes, it probably has to do with drummers hitting them too hard as well. I constantly remind myself to lay off of them when we play our harder songs.

I had a lot of success with experimenting with different mics. Before i knew better I'd have a 57 on the snare and the hi hat bleed sounded so horrible and loud.
Since switching to a small diaphragm condenser the bleed is nice and crisp and alot less of a problem all of a sudden.