I don't think trading on the grey sheets proves that MBST is a scam.
A few years back a good friend told me about a stock that was on the grey's. That company was Seadrill. Back then it was listed under SDRLF. I bought a boat load @ $6.00 a share and today it's @ $38.60..It's now listed as (SDRL)It also pays out a very nice dividend.
I am still worried about MBST..I thought they had a good product in the Karaoke machine..All I can do is wait and hope MBST makes a comback..Otherwise I'll loose a few thousand bucks..