I am only speaking from experience. When you sell large items that you cannot simply take to your local gas station (Appliances, TVs, Riding lawn mowers, Furniture, etc), you have no choice but to sell from your home base, so people will know where a seller resides and/or keeps their inventory. Using a secondary or cover phone number won't protect the seller. This is more geared to Full Time sellers because once you sell enough products, you eventually deal with weird, creepy, funky people from all sorts of backgrounds. Take proper security measures including surveillance cameras, neighborhood watch, equipping your home with a protective weapon or two, a dog, etc. and you won't bat an eye if someone shows up at your door asking weird questions because you've already protected your family, yourself and your property. Its just apart of the job.

Sure, if you are a young 19 year old single person that sells one thing per month maybe it would be a good idea. But the original question asked if I use a separate phone number to which I answered speaking from experience. Noting all of the above information, if you sell truthfully you should not have a problem. If you can't handle some person showing up unexpectedly, Id recommend another profession that is not consumer sales.