I totally sympathize with you. You have every reason to be cautious. I feel sorry for that salesman though, because he is just doing his job. Door to door selling is a legit job in TN. It is tough, but very rewarding. Here's the other part of the story that a lot of people need to know before you can generalize them as "scammers."
As a door-to-door sales rep for many years now, I have always had customers questioning my presence in their neighborhoods and even call the police on me several times. I do carry my peddler's/solicitors permit with me AT ALL TIMES, my company ID, company-issued business cards, my work phone, and most importantly, I do conduct myself in a professional manner regardless of how unreasonable a customer is. When I come to a house, I give as much info as the customers would require of me to make them comfortable speaking with me, in as much as I also require them to provide me info when I set-up the account. In my years of selling, there is not one customer who complained about me scamming them (except for those who have bad credit from the beginning) because I make everything clear in writing, and I do leave paperwork behind. They can reach our corporate office to verify my name and the account I have set-up for them. If they have issues about their service, we have a 24/7 hotline to take care of them if they cannot reach me through my cellphone.
I suspect that the man who knocked on your door is a contractor. Most door-to-door reps for Dish and DirectTV are commission-only. This may be the reason why the person who came to your door was being persistent. If he leaves without you signing up, more than likely, you would call the main office and set up the account through somebody else, and he would lose the credit for generating the sales lead. The salesperson may also be going through a tough situation as most of them do--his kid may be in the hospital, or his wife having a surgery, or his mother/father needing a transplant--for all we know. They are people too, and believe me, they might have compelling reasons why they are doing the job. And yes, they are also as concerned regarding their safety.
I would feel uneasy if I were in your shoes too. You do have every right to be concerned if the rep did not have any ID, or badge with him.
However, the knock being at 7:30pm on March 10 (which is "the other night" on your post) is not something too frightening because daylight savings time already kicked in. On March 10, sunsets did not start until 9pm. Ergo, it is not really "evening" or "late at night." The standard practice with us reps is that we knock until the sun is down or until our customer would not be able to recognize our faces anymore. We want you to be able to see us inasmuch as we want to see you.
We can also smell like smoke even if we don't smoke ourselves. This is because we don't mind stepping inside a smoker's house to set-up an account, and the stench may stay on our shirts and skin for hours. If we forgot to bring our extra shirt in the car, we just move on to the next house, til the next, and the next, until the smell robs off to a minute level.
As a sales rep, on a daily basis, I also think of the dangers that I have to face if I enter a customer's house. I can be subjected to different kinds of harm inside a home and I have no recourse if I will never be heard of after that. But I enjoy doing this job because it is very rewarding for me. To be able to help customers in my own community -- help them save and get more value for their money, and get better customer service--is in itself psychologically rewarding.
Even though I have offers from other companies (I do have a double Bachelor's Degree from a very reputable university and am working on my Master's), I did not take any of them. I am very fulfilled with the money I am making at a lesser amount of time and lesser amount of effort than what I was doing as a former Financial Analyst. I also have 2 foreign companies I am managing on the side when I am not outside knocking. I am graduating with no student loans, paid off my cars, no kids to support and owe nothing but my home mortgage.
To state the obvious, not all door to door sales reps are like this man. We can be as professional as you want us to be. We went through stringent background screening and drug testing, taking a company exam and getting licensed for what we are selling.
Most of us leave our door hangers with our contact info if nobody answers the door. So if you are uncomforable meeting with us on the day we came to your doorstep, we can do business over the phone and/or you can always research about us (or our names in Google) before scheduling an appointment with us. Many of us would not mind that. In fact, I strongly encourage you to do so.
I hope this response makes you feel more comfortable living in your neighborhood.