I have noticed that some manufacturers of audio processing products label a 2nd order Butterworth low pass as having a slope of 12dB per octave, but then also label a 2nd order Butterworth band pass as having a slope of 12dB per octave. In actuality each side of a 2nd order Butterworth band pass has a slope of only 6dB per octave. Is there a convention that because it is symmetrical that the slope of each together constitute the "slope" or is it just that they are wrongly assuming that order is equivalent to slope for all the Butterworth filter types?
By convention, the pole count refers to the number of poles in the design polynomial (Butterworth, Chebyshev, etc) and this defines the amount of roll off in the stop band.
If we maintain this convention, then all filters roll off at the rate of 6 dB / octave / pole in the stop band, whether it is a low pass, high pass, band pass, or notch.
Also, a nth order Elliptic has the same ultimate roll off rate in the stop band as a nth order Butterworth. Of course, the Elliptic's transition band will be much narrower.