[Historybuff]

When they respond to your ad, they don't refer to it in particular
saying something like "I am interested in what you have for sale..."
that way they can use the same letter for many more advertisers.

And by the way to make you feel really dumb, you may at this first stage
be talking to a robot. The robots fire the first responses and then if they get an answer, maybe one or two levels up a real human being begans "working you" to get some money out of you or to get information like your bank account number, SS number etc. Once they have permission to send money to your account, they can fake a letter to the bank allowing them to extract money from it and you are toast.

I find that many of these scammers are in Nigeria or some place that had a former British influence so they occasionally tip off their origin by using a word that Americans don't use anymore like "whilst" or "lorry" for truck, etc.