There are getting to be more and more of these fakes out there, I got a fake Beta 87a on an EbAy auction, I will not state the auction number pending action..
The first thing found was the mic was not even a condenser! turn off your phantom power if you can and see if it still works, if it does you have yourself a fake.
Secondly the mic's weight is a lot lighter, also even tho the bottom connector has the silver bar by the pins it is more of a matt grey color instead of a semi to glossy black, I got a Beta 57a and on both the pin numbers are smaller and very difficult to read.
The fake sm58's foam on the top of the capsule is black, on the legit ones it is grey , on all the fakes the sound is brighter and the volumn is
somewhat hotter and not as full sounding..after playing with the EQ I did get a decent sound out of them but you would have to be a single mic act or eyeryone else would have to use one too...
Thr grill bottom on a real sm58 is slightly rounded on the bottom edge (not sharp and flat on the fake) I hope this helps.
The only thing we can do is sue the pants off these bums selling these, and get them kicked off the site they need to sell from (EbAy)
Also get their PayPal accounts deleted, EbAy in my opinion needs to get more proactive and make sure these guys are not name jumping
to get new accounts...