I must be one of the lucky ones, never had a butting wether. The current hairy yeti wouldnt even dream of it, I tell him enough times, "she dead, (meaning the useless pet ewe he keeps company) you gone, be warned!" (I wouldnt, but he doesnt need to know that!).
However, I've had stroppy ewes, ate one once, boy was she tough! Spite, I reckon! Now, if nasty, cull at auction.