It is not an absolute method, but it should give you an indication, if you know the impedance of the speaker you can use your ohm meter to check to see if the resistance is close to the listed impedance. But be aware that it is not the proper way to check for impedance, impedance is defended as resistance measured in ohms at a specific frequency. so as your speaker is producing sound, the resistance will vary greatly. But using an ohm meter will at least tell you if it is a dead short. It will tell you if one is bad, but it will not tell you if a speaker is good. It although will give more evidence that a speaker will be good.

what will the amp support ?

The problem with a static resistance measurement of a speaker is that the problem may be within the gap.  A speaker is nothing more than a coil supported by the cone and the spider (the flat round piece under the cone attached to the frame).  The spider and the surround (foam piece at the large end of the cone) keep the coil moving up and down straight.  If you have over heated the speaker by using too much power or because the amp is sending DC current as well as AC, the wires within the coil may come loose.  Only when the speaker is moving will the coil short against the frame and thus smoke the amp.  Try pushing carefully on the face of the cone to see if the coil moves freely.  Press straight and carefully.

I have reconed more speakers than I'd like to admit and usually a loose portion of the coil is the problem.  By the way a static measurement of 4.6 ohms or so is correct for an impedence of 6 ohms. An 8 ohm impedence will measure about 6 ohms or so.

Dan

Yes, you can, put your meter on the speaker terminals, and gently push in and out on the speaker as dan suggested, and see if the meter drops to a low resistance or opens up. Don't move it too fast, because a coil moving inside a magnet will produce a small amount of electricity that may throw off your meter. As Dan said it should move freely with no drag points. if it does the speaker is blown.