If you can be present, an estate sale can be monitored. Around here, they are now largely on line by auctioneers, where you can see the whole show. I am just amazed at what people will bid on their phones, even more so than live. Why? Who knows? Look at the auction listings in the local papers to see the auctioneers who do the job from photography to collecting the $$ to loading up the stuff.
The biggest lies are the fables they'll tell you about retirement communities. "Chef prepared meals." More like warmed over t.v. dinner quality.
The problem with on-premises sales is that you attract the garage-sale crowd who want to pay $5 for a hard wood dining table. The market is very limited, and casual tire-kickers are 90% of the traffic. Then you have to worry about the thieves who come by to pick off other property from your home when they are not being watched.
At least online you have a national, if not a world-wide market, and opportunities which come with it.