Sadly, the old-school, in-person scams still exist. Many of these are rip-offs rather than scams. I see a scam as a scheme to take your money or to gain access to something of value. A rip-off is when a company provides a good or service at an unreasonably high price. Beware of both.
I recall a door-to-door guy offering replacement windows. His presentation showed the utter fantastic-ness of his windows. Then came the price of something like $6,000 for a large living room window. That price is not just high, but stratospheric (or perhaps low-Earth orbit high). He graciously offered to sell just the window so that I could install it and save money. That price was somewhere in around $3,000. Afterwards, I called a local company that offered a lifetime guarantee window for around $700. The low cost surprised me. A similar window with sliders on both sides was about $750. Installation added around $100. So, for about $850 that would install a new, giant living room window, with sliders, and a lifetime guarantee. I asked about replacing all of my very old windows and the grand total came to about $1500ish. For about half of the price of the rip-off window I got all new windows. The two installation guys were finished in less than two hours. That was quite impressive to watch.
The first window guy was not a scammer but that was definitely a rip-off. Other rip-offs include pest control, security systems, lawn care, etc. These are legitimate people that come door-to-door but do not agree to anything on-the-spot. If you are interested in their services then take their contact information and then shop around. When they say that this is a one-time only price then I end the conversation and pass on the deal.
Some door-to-door sales people could be casing your property. Some will try to gain access into your house. These could include people selling vacuum cleaners, security systems, etc. If you let them into your house then they can see your belongings and possibly the type of security system that you have. If they see stuff that they like then you could get a visit from a burglar. This is probably not the case but it pays to be extra careful nowadays. The bottom line: do NOT allow them into your house.
A person “selling” a security system may ask if you have a security system already. If you say, “no” this is useful information for a burglar. I don’t think that most of these people are casing houses for further crimes but, that is a possibility. It is best not to give information as to security system about your house.
Don’t Be Stupid
Do not be stupid and give a flippant answer such as, “This house is insured by Smith & Wesson.” You just let an outsider know that you probably have one or more firearms and ammunition. Firearms are a prime target for theft. Do not give clues as to your security equipment or assets.