If you were purchasing from the markets for business purposes and getting fairly large shipments on a weekly basis, what are the chances that LE lets the packages come to you to build a case? Could they let packages come for months and record all the contents and record you taking packages? Can they build a case like this? From a more commercial standpoint with larger packages coming pretty frequently what precautions should be taken. OPSEC via computer is flawless, just concerned with accepting packages.
I've thought about this too... The thing is they would never know what something is unless they:
A. Sniped down your letter and further flagged your address
B. Found contents despite being in a MBB bag
C. Send it to a lab to be tested your shit to see what it is (Everytime)
D. Vacuum seal it back up
E. MBB it
F. Send it on its way in a timely fashion
Not very likely, but that's just my logic; I don't know this for sure, they could indeed be doing this but that's just my $0.02