I see this all the time here. Someone is anticipating a potential CD (admittedly in some cases it is more likely than others) and people tell them to "man up and just accept the package" or "refusing a package is more suspicious than just accepting it"
Yes it is true that most people would never refuse a package and it is a weird thing to do, but this is absolutely awful advice. CDs work based on conditional search warrants. If you don't know what that means there is an explanation here:
http://www.tmcec.com/public/files/File/Course%20Materials/FY11/Judges/search-warrants/powerpoint.pdf
Basically it boils down to the fact that you accepting a package that is known to contain an illicit substance into your residence is probable cause to get a warrant issued to search your residence. The police can't exactly wait for you to take the package before going to a judge to get a warrant since these things take some time and they don't want to give you any time to get rid of/stash things, so they get the warrant beforehand, but can only execute it on the condition that you accept the package.
If you haven't figured it out by now, what that means is that the police can have a warrant to search your residence but are only allowed to execute the raid IF you take the package into your possession. If you refuse a package, the conditions for the warrant will not be met and they will not be able to search your residence.
YES they can still attempt to harass you into giving them permission to enter (you should know by now to shut the fuck up and don't say anything or let them in)
YES there is still a chance that they can go back to the judge and potentially get a non conditional warrant, but there is a pretty good chance they won't get it unless they have some other evidence.
YES it is suspicious to refuse a package, and by doing so you will probably burn your address as well as the vendor's return address for that order (ALWAYS LET YOUR VENDOR KNOW IF THIS EVER HAPPENS SO THEY CAN CHANGE THEIR STEALTH)
YES many times suspected CDs turn out being nothing
But hell, willingly accepting a CD is essentially willingly letting the police into your home. If I had any reason to suspect that I was going to be the recipient of a CD there is no way I would ever just play along with it.
I'll end with some advice (take this with a grain of salt of course, as you should with any advice from this subreddit):
Pay attention to who your mailmain is and what their normal schedule is like. Order (legal) things from various places and see how long they take to get to you. Get used to what is normal so you can recognize it when things are off.
Never sign for a package containing an illicit substance. By now, no vendors should be using shipping methods that require a signature. CDs don't always require a signature so this definitely isn't going to save you completely, but it's a good rule to follow.
If a package ever goes missing or if you refuse a package, consider your address burned.
MOST IMPORTANTLY, keep a clean house whenever you order if possible, and definitely if you suspect a CD. If there is nothing in your home for the police to find, there is nothing they can do.
I've seen a lot of sloppy advice and behavior throughout this sub and I really think it's bad for the community. Yes many times things turn out to be nothing but how much do you value your freedom? Those who get comfortable are the ones who get caught.
Stay safe
Because they are fucking idiots with little clue as to how any of this works. Majority of the people here have never even made a purchase and are just talking out of their ass.