Why do people pay dowsers to tell them where to dig a well? Why do people - some very intelligent - pay a fortune teller to tell them their future? Why do people - some very intelligent - tithe to protect their soul in the afterlife?
Never underestimate how easy it is to separate a desperate man from his money.
Of course you can. Here's three types of cons that would work on honest men:
1) Romance scams: The con artist develops a relationship with the target (mark). The con artist then develops a range of fraudulent reasons that they need money from the mark, from needing the money to travel to the mark's country to see them to needing the money for cancer treatment.
2) Various fake medical cures. There's a huge industry of these preying on cancer victims, for instance.
3) The melon drop: a scammer will pretend to bump into the mark and drop a package that's already broken, then demand compensation.
There are many, many more. Merely being "honest" is no protection.
I hate that expression. Of course you can con an honest man.
For example, you could set up a high quality internet store offering, say, cameras for a few dollars less than everyone else. There is nothing dishonest about buying from there - it is simply trying to get a good deal. And yet if the store then simply takes the money and sends nothing, they have indeed conned an honest man.
Never underestimate how easy it is to separate a desperate man from his money.
And the the related: you can't con an honest man.