I just had an interesting idea about this, say someone wanted to start a dark net operation (think DrXanax level) for the hell of it, and owned a relatively popular shop where they shipped out regular clearnet packages.
Could someone theoretically who owned this shop, use their own return address to send out packages? If the police catch the return address and start investigating them for drugs, could they say they had no idea and someone else was using their return address?
It might be so fucking stupid that it could actually work. You could walk into the post office everyday with 10 clearnet packages and 10 counterfeit xanax packages and ship them out without raising any suspicion. And the police would be chasing a lead that someone else is doing it.
???
The main issue is that it could put the spotlight on you when you otherwise would have been unknown to LE. The only narrow situation it helps is if you get a pack returned it will come back to you. But that's a very narrow situation. You can bet LE would do their due diligence so you better make sure you are fucken spotless. To me the risks don't outweigh the benefits.
I'm no expert in vendor opsec but I think I'd rather be "unknown" than have a spotlight on my business where the link could conceivably be uncovered. You potentially give LE a great starting point.