Starts with something vague, idle chat about the boat, compliments about the boat etc. There is a big reluctance to phone you,they SMS/text, or email via the website you are using. I had someone ask me to phone him,I thought, why doesn`t he phone me if he wants info, so I didn`t, and no follow up ever happened. One guy I actually phoned using a service which does not send my number,someone did answer, but his later contact attempts were still SMS.
I suppose you could miss someone genuine who accidentally fits the pattern and gets ignored, but it is unlikely. After a while the pattern and patter was obvious, sometimes I think it was the same scammer trying again with a different name.
A sale contract could require settlement at your bank, with a bank(?certified or cashier`s in USA) cheque drawn on one of 4 nominated banks(our big 4 banks), that way no giving out a/c numbers. I`d insist on a contract, not just payment,to regulate the deal, but I guess long before that they are gone if they are a scammer.