...The test is simplicity itself; you lightly stroke the bow along its length and compare this sound to that of the a similar light stroke down the back plate of the instrument in question. Rember to do this with care as we do not want to scratch the varnish of the instrument. You can even do this with a clean fingertip in a quiet room with good acoustics. A soft wood (unsharpened) pencil might be a useful tool also.
...After you narrow the selection to matched 'rub tone' bows, selecting the bow which most closely matches the tap tone of the back of the instrument (listening for the lowest part of the 'tap tone'). Here the downward tap on the top of the bow wood, along it's length, is the one we are interested in. The best bow is the one where the lowest part of the tap tone is the same from one end of the frog or the bow to the tip. (The high overtones of the tap tone will change with the position of the tap on the bow.)
...Final selection between the remaining possible bows is then made on 'feel' and bow action when playing.
...I believe that if you use this three part guide in making your next bow selection, you will be pleased with the results!